摘要 :
All optical networks have emerged as a solution to constantly increasing throughput demands. Here, optical data are transmitted over long distances without the need for optical-electrical-optical conversion. The major limitation w...
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All optical networks have emerged as a solution to constantly increasing throughput demands. Here, optical data are transmitted over long distances without the need for optical-electrical-optical conversion. The major limitation with all optical networks is crosstalk, which results from the leakage of signals routed in optical switches with the desired signal. Optical components such as cross-connectors, routers, and add-drop multiplexers are prone to crosstalk. Intra-channel crosstalk results from the leakage of signals with the same wavelength as the transmitted signal. Furthermore, crosstalk can also be classified as coherent and incoherent depending on the laser phase noise of the signal and interferers. Inter-channel crosstalk occurs when both the transmitted signal and interferers have different wavelengths. Routing and adding-dropping signals in optical networks are a key factor to get high flexibility and transparency of the system. The effect of crosstalk in optical components is explained in this paper and, in particular, optical crosstalk regarding cross connectors and add-drop multiplexers is presented. An improved expression for Bit Error Rate as a function of input power is proposed
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摘要 :
Vehicles searching for on-street parking create an environmental and economic impact through
increasing network traffic flow and congestion, heightening pollutant emission levels, creating
additional noise, giving rise to time d...
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Vehicles searching for on-street parking create an environmental and economic impact through
increasing network traffic flow and congestion, heightening pollutant emission levels, creating
additional noise, giving rise to time delays for through vehicles, and leading to potential safety
hazards caused by vehicles manoeuvring into or out of on-street parking-spaces. Despite extensive
negative externalities for individual drivers and society, parking search is a little researched area.
The aim of this paper is to review and identify factors which influence an individual’s on-street
parking search decisions. These factors have been found to comprise time costs, parking pricing, area wide
parking policy, personal and socio-economic characteristics. The paper will also examine the
methodological and modelling approaches which have been applied to on-street parking search.
The paper concludes with identification of potential future research directions, which will seek to
investigate factors influencing parking search behaviour across other cities and countries, enabling
inter-spatial comparisons of influencing factors. Quantification of economic, environmental, and
safety impacts of parking search by examining the contribution made by vehicles searching for
parking, as distinct from the impact arising from through traffic, would be a further important research
area. The findings have potential urban parking policy applications, which could reduce the number of
vehicles searching for parking, with associated environmental and economic benefits.
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摘要 :
Vehicles searching for on-street parking create an environmental and economic impact through
increasing network traffic flow and congestion, heightening pollutant emission levels, creating
additional noise, giving rise to time del...
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Vehicles searching for on-street parking create an environmental and economic impact through
increasing network traffic flow and congestion, heightening pollutant emission levels, creating
additional noise, giving rise to time delays for through vehicles, and leading to potential safety
hazards caused by vehicles manoeuvring into or out of on-street parking-spaces. Despite extensive
negative externalities for individual drivers and society, parking search is a little researched area.
The aim of this paper is to review and identify factors which influence an individual’s on-street
parking search decisions. These factors have been found to comprise time costs, parking pricing, area wide
parking policy, personal and socio-economic characteristics. The paper will also examine the
methodological and modelling approaches which have been applied to on-street parking search.
The paper concludes with identification of potential future research directions, which will seek to
investigate factors influencing parking search behaviour across other cities and countries, enabling
inter-spatial comparisons of influencing factors. Quantification of economic, environmental, and
safety impacts of parking search by examining the contribution made by vehicles searching for
parking, as distinct from the impact arising from through traffic, would be a further important research
area. The findings have potential urban parking policy applications, which could reduce the number of
vehicles searching for parking, with associated environmental and economic benefits.
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摘要 :
Currently in the UK, carbon emissions associated with businesses activities has moved
from policy requirements to definitive legal responsibilities following the UK's Climate
Change Act (CCA) in 2008. Real and pressing need exists...
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Currently in the UK, carbon emissions associated with businesses activities has moved
from policy requirements to definitive legal responsibilities following the UK's Climate
Change Act (CCA) in 2008. Real and pressing need exists for a flexible and easy to use
technique to enable businesses to assess their carbon emissions; following recent changes
in legislation and regulations on environmental impacts of construction activities. The
aim of this paper is to develop a methodology that can offer businesses a carbon Life
Cycle Assessment (LCA) tool to identify emissions "hotspots" across its value chain, and
inform a carbon reduction hierarchy.
The approach employed is based on the methodology described in the Publicly Available
Specification (PAS2050) protocol. The objective of the method is to identify where the
largest production of emissions exists and provides for the biggest potential reduction
within routine highway maintenance processes. The developed methodology framework
offers businesses the potential to make informed decisions in carbon terms, by identifying
and prioritizing areas of potential emissions reduction.
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摘要 :
Currently in the UK, carbon emissions associated with businesses activities has moved
from policy requirements to definitive legal responsibilities following the UK's Climate
Change Act (CCA) in 2008. Real and pressing need exis...
展开
Currently in the UK, carbon emissions associated with businesses activities has moved
from policy requirements to definitive legal responsibilities following the UK's Climate
Change Act (CCA) in 2008. Real and pressing need exists for a flexible and easy to use
technique to enable businesses to assess their carbon emissions; following recent changes
in legislation and regulations on environmental impacts of construction activities. The
aim of this paper is to develop a methodology that can offer businesses a carbon Life
Cycle Assessment (LCA) tool to identify emissions "hotspots" across its value chain, and
inform a carbon reduction hierarchy.
The approach employed is based on the methodology described in the Publicly Available
Specification (PAS2050) protocol. The objective of the method is to identify where the
largest production of emissions exists and provides for the biggest potential reduction
within routine highway maintenance processes. The developed methodology framework
offers businesses the potential to make informed decisions in carbon terms, by identifying
and prioritizing areas of potential emissions reduction.
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摘要 :
Congestion is a significant cost to society, amounting to somewhere between 1 and 2% of GDP
according to an EU-wide survey. Accordingly, in 2000 the UK government enacted legislation that
enabled local authorities to introduce...
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Congestion is a significant cost to society, amounting to somewhere between 1 and 2% of GDP
according to an EU-wide survey. Accordingly, in 2000 the UK government enacted legislation that
enabled local authorities to introduce new policy instruments to address this - a Road User Charge
and/or a Workplace Parking Levy (WPL). Interestingly however, to date only one local authority,
Nottingham City Council, has decided to introduce a WPL. The WPL in Nottingham is a charge
placed on employers in the city with 11 or more employee parking spaces with all the revenue
hypothecated for local transport improvements. The purpose of this paper is to present the results of a
post-implementation study of the Nottingham WPL. Specifically it seeks to understand the reasons
why and the factors that allowed Nottingham to introduce a WPL. It aims to highlight the issues, the
short term and anticipated long term impact, as well as the likelihood of a WPL being implemented by
other authorities in the UK. It achieves this through a document review and thirty semi-structured
interviews with key stakeholders. It was found that although for some the cost of the levy is not
sufficient enough to deter car use and/or the alternatives are not adequate, it is expected that some
people will change travel behaviour over the life of the scheme. Thus such schemes can have a
positive impact on congestion and are able to deliver many wider benefits if integrated as part of a
long term strategy.
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摘要 :
Congestion is a significant cost to society, amounting to somewhere between 1 and 2% of GDP
according to an EU-wide survey. Accordingly, in 2000 the UK government enacted legislation that
enabled local authorities to introduce n...
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Congestion is a significant cost to society, amounting to somewhere between 1 and 2% of GDP
according to an EU-wide survey. Accordingly, in 2000 the UK government enacted legislation that
enabled local authorities to introduce new policy instruments to address this - a Road User Charge
and/or a Workplace Parking Levy (WPL). Interestingly however, to date only one local authority,
Nottingham City Council, has decided to introduce a WPL. The WPL in Nottingham is a charge
placed on employers in the city with 11 or more employee parking spaces with all the revenue
hypothecated for local transport improvements. The purpose of this paper is to present the results of a
post-implementation study of the Nottingham WPL. Specifically it seeks to understand the reasons
why and the factors that allowed Nottingham to introduce a WPL. It aims to highlight the issues, the
short term and anticipated long term impact, as well as the likelihood of a WPL being implemented by
other authorities in the UK. It achieves this through a document review and thirty semi-structured
interviews with key stakeholders. It was found that although for some the cost of the levy is not
sufficient enough to deter car use and/or the alternatives are not adequate, it is expected that some
people will change travel behaviour over the life of the scheme. Thus such schemes can have a
positive impact on congestion and are able to deliver many wider benefits if integrated as part of a
long term strategy.
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摘要 :
Transport accessibility to healthcare facilities is a major issue in the United Kingdom, as recently
demonstrated by the shift away from „providing healthcare in acute hospitals‟ to „care closer to home‟.
However, it is not ...
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Transport accessibility to healthcare facilities is a major issue in the United Kingdom, as recently
demonstrated by the shift away from „providing healthcare in acute hospitals‟ to „care closer to home‟.
However, it is not easy to measure transport accessibility since it is often highly subjective and
deterministic. Common measures of accessibility focus on the creation of distance or travel time contours
around a destination and devote less attention to individual differences such as users‟ perception, their
transport usage and area-wide factors.
The aim of this paper is to develop a user-based accessibility model by focusing on both individual
transport usage (i.e. access to different transport modes and fuel consumption) and area-wide factors (e.g.
transport network, public transport provision, safety/security and area deprivation). A questionnaire
survey was carried out to measure users‟ perceptions of the accessibility to various healthcare facilities.
The responses are integrated with various datasets obtained from a range of secondary sources (e.g.
National Census, Ordnance Survey, Deprivation Indices) using a GIS technique. A multilevel (i.e.
individuals nested within local areas) mixed-effects statistical model is employed to develop a
relationship between user perception on the accessibility and the factors influencing accessibility.
The initial results suggest that travel distance by car, number of available bus services, age and
destinations affect accessibility to healthcare facilities. Based on the weighting of each of the factors, a
range of policies can be developed that could lead to the reduction in health inequality in terms of fair
access to healthcare provision.
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摘要 :
Transport accessibility to healthcare facilities is a major issue in the United Kingdom, as recently
demonstrated by the shift away from ?providing healthcare in acute hospitals? to ?care closer to home?.
However, it is not easy t...
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Transport accessibility to healthcare facilities is a major issue in the United Kingdom, as recently
demonstrated by the shift away from ?providing healthcare in acute hospitals? to ?care closer to home?.
However, it is not easy to measure transport accessibility since it is often highly subjective and
deterministic. Common measures of accessibility focus on the creation of distance or travel time contours
around a destination and devote less attention to individual differences such as users? perception, their
transport usage and area-wide factors.
The aim of this paper is to develop a user-based accessibility model by focusing on both individual
transport usage (i.e. access to different transport modes and fuel consumption) and area-wide factors (e.g.
transport network, public transport provision, safety/security and area deprivation). A questionnaire
survey was carried out to measure users? perceptions of the accessibility to various healthcare facilities.
The responses are integrated with various datasets obtained from a range of secondary sources (e.g.
National Census, Ordnance Survey, Deprivation Indices) using a GIS technique. A multilevel (i.e.
individuals nested within local areas) mixed-effects statistical model is employed to develop a
relationship between user perception on the accessibility and the factors influencing accessibility.
The initial results suggest that travel distance by car, number of available bus services, age and
destinations affect accessibility to healthcare facilities. Based on the weighting of each of the factors, a
range of policies can be developed that could lead to the reduction in health inequality in terms of fair
access to healthcare provision.
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摘要 :
National Parks in the UK are increasingly facing issues of traffic congestion,
environmental degradation and pressures from competing stakeholders. These pressures are
exacerbated by the fact that the National Parks Authority do...
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National Parks in the UK are increasingly facing issues of traffic congestion,
environmental degradation and pressures from competing stakeholders. These pressures are
exacerbated by the fact that the National Parks Authority does not have overall control for
policy within the national parks.
This paper draws on an extensive literature review to provide a brief overview of
National Parks in the UK, the transport issues encountered by these National Parks and the
planning and policy responses to them. Within this, the paper covers three specific aspects
namely: opposition to traffic restraint where schemes proposing any form of vehicle
restriction can be opposed at the local level, making their introduction publicly and politically
unacceptable; initiatives can fail to meet conventional measures of success and as such
schemes can be abandoned due to poor patronage or failure to meet pre-determined economic
or social criteria; and finally in terms of planning and management practicalities: initiatives
can be difficult to enforce across dispersed areas (for example parking strategies); funding for
initiatives can be limited and short-term in nature; and activities can be difficult to coordinate
and rely on the participation on a wide range of stakeholders.
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