Exploiting the Design Freedom of RM

This paper details how Rapid Manufacturing (RM) can overcome the restrictions imposed by the inherent process limitations of conventional manufacturing techniques and become the enabling technology in fabricating optimal products. A new design methodology capable of exploiting RM’s increased design freedom is therefore needed. Inspired by natural world structures of trees and bones, a multi-objective, genetic algorithm based topology optimisation approach is presented. This combines multiple unit cell structures and varying volume fractions to create a heterogeneous part structure which exhibits a uniform stress distribution.Mechanical Engineerin

Assessing the status and distribution of nesting herons in urban areas of lower Tidewater, Virginia (2018 breeding season)

Twenty-five species of colonial waterbirds nest in Virginia including herons, egrets, ibises, gulls, terns, skimmers, cormorants, and pelicans. A coalition of agencies, organizations and individuals has systematically surveyed waterbird nesting colonies throughout the Coastal Plain periodically since 1993. The objectives of these surveys have been to develop timely data resources that may be used for environmental review and to assess long-term trends in breeding populations. The 2018 survey represents a continuation of the series. The objective of the sub-project reported here was to survey heronries throughout urban areas of lower Tidewater including the cities of Newport News, Hampton, Norfolk, Virginia Beach, and Portsmouth. We surveyed lower Tidewater for heron colonies between 10 April and 3 July, 2018 by systematically driving or walking through neighborhoods and other urban areas. We mapped and surveyed 90 heronries that supported great egrets, yellow-crowned night herons and green herons. Colony size varied from 2 to 259 breeding pairs with 79% below 10 pairs and 93% below 20 pairs. The total number of breeding pairs has increased by nearly 30% since 2003 but is comparable to the number found in 1993. The number of colonies has increased steadily over time and is more than double that found in 1993. The increase is due entirely to the proliferation (30 vs 86) of yellow-crowned night herons over this time. The number of colonies of great egrets (7 vs 3) and green herons (11 vs 4) has declined over this same time. Population changes of herons within urban areas should be viewed within the larger context of the state-wide population. Great egrets continue to expand their breeding range westward in Virginia and the broader population has increased significantly over the past 30 years. However, tension continues between urban-nesting pairs and landowners and several breeding locations have been lost. Urban-nesting pairs of yellow-crowned night herons represent a significant percentage of the state-wide population. Yellow-crowns have been declining within other breeding locations but have experienced resurgence within urban areas. Although green herons breed widely throughout the state, population estimates have always been poor due to the difficulty of surveying for them. Several important breeding sites within urban areas have been lost over the past 30 years resulting in a significant decline of the known population. Causes for these losses remain unclear

Virginia Peregrine Falcon monitoring and management program: Year 2016 report

The peregrine falcon (Falco peregrinus) was believed to be extirpated as a breeding species in Virginia by the early 1960s. An aggressive restoration program was initiated in 1978 that included the release of 115 captive-reared birds on the Coastal Plain (1978-1985) and 127 birds in the mountains (1985-1993). This program resulted in the first breeding of the modern era in 1982. Since this time, the population has proceeded through a rapid establishment phase followed by a consolidation phase. However, more than 95% of all breeding activity over the past 30 years has occurred on the Coastal Plain with very limited breeding within the historic mountain range. Since 2000 a dedicated translocation program has moved more than 250 birds from eyries on the coast to hack sites in the mountains in an effort to restore the mountain breeding population. Restoration of the breeding population in the mountains continues to be a management priority for the state. In 2016, Virginia supported a known falcon population of 31 breeding pairs including 28 within the Coastal Plain, 1 in the Piedmont and 2 in the mountains. This represents the largest population ever recorded in the state and the fourth consecutive year that the population has exceeded 25 breeding pairs. New breeding territories were documented on a building in Virginia Beach and a bridge in Norfolk. 2016 was a difficult breeding year with only 49 (57%) of 85 eggs hatching and several late breeding attempts. The reproductive rate (1.58 young/occupied territory) was considerably lower than in recent years. The population continues to benefit from the efforts of a large community of agencies, corporations and individuals. Efforts continued in 2016 to identify breeding adults via field-readable bands to better understand dispersal and demography throughout the mid-Atlantic region. The banding status of 45 (71%) of the 63 adult peregrines known within the breeding population was determined. Twelve (26%) of the 45 birds were unbanded. The level of unbanded birds suggests the possibility of unknown eyries within Virginia or surrounding states. Of the banded birds where state of origin could be determined, 20 were from VA, 6 from NJ and 2 from MD. The alpha-numerics were read for 29 adults and of these the USGS bands have been recorded for 27. The natal territories were determined for 24 adults. Birds ranged in age from 1 to 16 years old. Efforts to identify marked peregrines should continue since these birds are contributing to our understanding of effective population size and regional management. Bands for 12 additional falcons were read and reported over the past year. Six of these birds originated in Virginia and were found breeding in other states including a male and female in Pennsylvania and 4 females in New Jersey. Three birds were captured during fall trapping operations on Assateague and Cape May Point. A first-year bird male was found dead and a first-year female was photographed multiple times on Chincoteague National Wildlife Refuge. A first-year female was found injured near Topton, PA and rehabbed over several months and released

Virginia Peregrine Falcon Monitoring and Management Program: Year 2020 Report

The peregrine falcon (Falco peregrinus) was believed to be extirpated as a breeding species in Virginia by the early 1960s. An aggressive restoration program was initiated in 1978 that included the release of 115 captive-reared birds on the Coastal Plain (1978-1985) and 127 birds in the mountains (1985-1993). This program resulted in the first breeding of the modern era in 1982. Since this time, the population has proceeded through a rapid establishment phase followed by a consolidation phase. However, more than 95% of all breeding activity over the past 30 years has occurred on the Coastal Plain with very limited breeding within the historic mountain range. Since 2000 a dedicated translocation program has moved more than 250 birds from eyries on the coast to hack sites in the mountains in an effort to restore the mountain breeding population. Restoration of the breeding population in the mountains continues to be a management priority for the state. In 2020, Virginia supported a known falcon population of 32 breeding pairs including 26 within the Coastal Plain, 3 in the Piedmont and 3 in the mountains. This is the highest population recorded in the state and represents the third consecutive year that the population has exceeded 30 breeding pairs. New pairs were discovered on Jump Mountain and in an abandoned quarry along the Occoquan River. The 2020 breeding season was the second most productive in the state’s history producing 58 young. A minimum of 89 eggs were laid with at least 62 hatching. Only 4 (6.5%) of the 62 hatchlings did not survive to banding age. The reproductive rate was 1.87 young/occupied territory. Of 18 clutches that were followed completely from laying to fledging, 46 of 70 (65.7%) of eggs hatched and 44 of 46 (95.6%) of young survived to banding age. Four young were known to have problems after fledging including 3 birds that were recovered on the ground in Norfolk, Richmond and Reston and were taken for rehab. A male that was hacked from Franklin Cliffs was picked up in Timberville and later died. Efforts continued in 2020 to identify breeding adults via field-readable bands to better understand dispersal and demography throughout the mid-Atlantic region. The banding status of 55 (85.9%) of the 64 adult peregrines known within the breeding population was determined. Fourteen (25.5%) of the 55 birds were unbanded. The alpha-numerics were read for 34 adults and of these the USGS bands have been recorded for 31. Of the banded birds where state of origin could be determined, 26 were from VA, 5 from MD, 2 from NJ, 1 from DE and 1 from PA. Birds ranged in age from 2 to 19 years old. During the 2020 season, 3 young falcons (all males) were translocated to Shenandoah National Park and hacked. Birds were released on 13 June, 2020 and were fine on release. Six addled falcon eggs were recovered during the 2020 season from 4 eyries

Virginia peregrine falcon monitoring and management program: Year 2018 report

The peregrine falcon (Falco peregrinus) was believed to be extirpated as a breeding species in Virginia by the early 1960s. An aggressive restoration program was initiated in 1978 that included the release of 115 captive-reared birds on the Coastal Plain (1978-1985) and 127 birds in the mountains (1985-1993). This program resulted in the first breeding of the modern era in 1982. Since this time, the population has proceeded through a rapid establishment phase followed by a consolidation phase. However, more than 95% of all breeding activity over the past 30 years has occurred on the Coastal Plain with very limited breeding within the historic mountain range. Since 2000 a dedicated translocation program has moved more than 250 birds from eyries on the coast to hack sites in the mountains in an effort to restore the mountain breeding population. Restoration of the breeding population in the mountains continues to be a management priority for the state. In 2018, Virginia supported a known falcon population of 32 breeding pairs including 28 within the Coastal Plain, 1 in the Piedmont and 3 in the mountains. This is the highest population ever recorded in the state and represents the sixth consecutive year that the population has exceeded 25 breeding pairs. A new breeding territory was documented on a crane within the Norfolk Naval Shipyard. Long-time territories including the Norris Bridge and the Highrise Bridge (I-64) were vacant in 2018. A single adult male was observed on the I-295 bridge across the James River. 2018 was a mixed breeding year with a relatively low hatching rate (67%, 45 of 67 eggs hatched) and no losses before banding. Three young were known to be lost after fledging. Of 17 clutches that were followed completely from laying to fledging, 36 of 57 (63%) eggs hatched and 36 of 36 (100%) young survived to banding age. The reproductive rate (1.25 young/occupied territory) was considerably lower than in recent years. Efforts continued in 2018 to identify breeding adults via field-readable bands to better understand dispersal and demography throughout the mid-Atlantic region. The banding status of 46 (73%) of the 64 adult peregrines known within the breeding population was determined. Thirteen (28%) of the 46 birds were unbanded. The alpha-numerics were read for 29 adults and of these the USGS bands have been recorded for 27. Of the banded birds where state of origin could be determined, 22 were from VA, 3 were from NJ, 4 were from MD and 1 was from PA. The natal territories were determined for 27 adults. Birds ranged in age from 3 to 18 years old. Bands for 9 additional falcons were read and reported over the past year. Six of these birds (1 male, 5 females) originated in Virginia and were found breeding in other states (Table 5). This included 4 birds in Pennsylvania and 2 birds in New Jersey. A 10-year male banded on Watts Island was resighted in Talbot County, MD on 14 December, 2017. A hatch-year male banded in Reston Town Center was resighted on 27 June, 2018 in Loudon County, VA. A 13-year male banded on Benjamin Harrison Bridge and later hacked on Little Stony Man within Shenandoah National Park was photographed at Dyke Marsh in Alexandria, VA on 4 January, 2019

Virginia peregrine falcon monitoring and management program: Year 2017 report

The peregrine falcon (Falco peregrinus) was believed to be extirpated as a breeding species in Virginia by the early 1960s. An aggressive restoration program was initiated in 1978 that included the release of 115 captive-reared birds on the Coastal Plain (1978-1985) and 127 birds in the mountains (1985-1993). This program resulted in the first breeding of the modern era in 1982. Since this time, the population has proceeded through a rapid establishment phase followed by a consolidation phase. However, more than 95% of all breeding activity over the past 30 years has occurred on the Coastal Plain with very limited breeding within the historic mountain range. Since 2000 a dedicated translocation program has moved more than 250 birds from eyries on the coast to hack sites in the mountains in an effort to restore the mountain breeding population. Restoration of the breeding population in the mountains continues to be a management priority for the state. In 2017, Virginia supported a known falcon population of 29 breeding pairs including 26 within the Coastal Plain, 1 in the Piedmont and 2 in the mountains. This represents the fifth consecutive year that the population has exceeded 25 breeding pairs but is 2 pairs less than the record year of 2016. New breeding territories were documented on a smokestack along the Rappahannock River and a bridge across the Chickahominy River. Long-time territories including the Norris Bridge, Watts Island and the Highrise Bridge (I-64) were vacant in 2017. Single birds were observed on the I-295 bridge across the James and on Stony Man within Shenandoah National Park. 2017 was a mixed breeding year with a relatively high hatching rate (81%, 56 of 69 eggs hatched) but some losses both before banding (16.1%, 9 of 56 young lost) and after fledging (3 young known to be lost post-fledging). Of 21 clutches that were followed completely from laying to fledging, 41 of 53 (77.4%) eggs hatched and 35 of 41 (85.4%) young survived to banding age. The reproductive rate (1.62 young/occupied territory) was considerably lower than in recent years. Efforts continued in 2017 to identify breeding adults via field-readable bands to better understand dispersal and demography throughout the mid-Atlantic region. The banding status of 47 (81%) of the 58 adult peregrines known within the breeding population was determined. Ten (21%) of the 47 birds were unbanded. The alpha-numerics were read for 29 adults and of these the USGS bands have been recorded for 26. Of the banded birds where state of origin could be determined, 22 were from VA, 5 from NJ and 3 from MD. All three of the unknown birds had silver USGS and were likely from MD. The natal territories were determined for 25 adults. Birds ranged in age from 2 to 17 years old. Bands for 12 additional falcons were read and reported over the past year. Seven of these birds (all females) originated in Virginia and were found breeding in other states (Table 5). This included 3 birds in Pennsylvania and 4 birds in New Jersey. A second-year female was photographed multiple times on Chincoteague National Wildlife Refuge. A hatch-year male from Richmond was photographed in Lyndhurst, NJ and a hatch-year female that had been hacked in Shenandoah National Park was photographed near Silver Lake in Rockingham County, VA. A 5-year old female was identified in Westchester, NY during the early breeding season and may have been on territory

Virginia peregrine falcon monitoring and management program: Year 2019 report

The peregrine falcon (Falco peregrinus) was believed to be extirpated as a breeding species in Virginia by the early 1960s. An aggressive restoration program was initiated in 1978 that included the release of 115 captive-reared birds on the Coastal Plai

Dynamics of opinion formation in a small-world network

The dynamical process of opinion formation within a model using a local majority opinion updating rule is studied numerically in networks with the small-world geometrical property. The network is one in which shortcuts are added to randomly chosen pairs of nodes in an underlying regular lattice. The presence of a small number of shortcuts is found to shorten the time to reach a consensus significantly. The effects of having shortcuts in a lattice of fixed spatial dimension are shown to be analogous to that of increasing the spatial dimension in regular lattices. The shortening of the consensus time is shown to be related to the shortening of the mean shortest path as shortcuts are added. Results can also be translated into that of the dynamics of a spin system in a small-world network.Comment: 10 pages, 5 figure

Identity and Search in Social Networks

Social networks have the surprising property of being "searchable": Ordinary people are capable of directing messages through their network of acquaintances to reach a specific but distant target person in only a few steps. We present a model that offers an explanation of social network searchability in terms of recognizable personal identities: sets of characteristics measured along a number of social dimensions. Our model defines a class of searchable networks and a method for searching them that may be applicable to many network search problems, including the location of data files in peer-to-peer networks, pages on the World Wide Web, and information in distributed databases.Comment: 4 page, 3 figures, revte