The landlocked countries are the one without access to the sea and can be assimilate as countries around the world with a disadvantage of geography situation location. Chad and the Central African Republic are two of ...The landlocked countries are the one without access to the sea and can be assimilate as countries around the world with a disadvantage of geography situation location. Chad and the Central African Republic are two of the 40 landlocked countries around the world that transport 80% of their goods by road and rail, and as much as almost more than 50% of their passengers through a transit country with a transit transport system which is crucial for their trade and exchanges. The study aims to introduce the importance to have a good and efficiency transport network infrastructure in Central Africa to facilitate the trade for the landlocked countries of Central Africa (Chad and the Central African Republic), member of CEMAC trade area and proposes some measures that can be adopt</span><span style="font-family:"">ed</span><span style="font-family:""> to improve their conditions and ameliorate the trade for those countries.展开更多
Recent innovations in transport technology are now providing mobility that is cheaper, autonomous, electric, and with improved ride quality. While much of the world’s attention has been on how this can be applied to ...Recent innovations in transport technology are now providing mobility that is cheaper, autonomous, electric, and with improved ride quality. While much of the world’s attention has been on how this can be applied to cars, there have been rapid adoption of these and other technologies in High Speed Rail and Metro Rail systems that run between and across cities. This paper shows how such innovations have now been applied to create the next generation of urban transit system called a Trackless Tram. Trackless Trams are effectively the same as traditional light rail except they run on rubber tyres avoiding disruption from construction for Light Rail, but they retain the electric propulsion (with batteries) and have high ride quality due to rail-type bogies, stabilization technologies and precision tracking from the autonomous optical guidance systems—with infrastructure costs reduced to as low as one tenth of a Light Rail system. As with Light Rail, a Trackless Tram System provides a rapid transit option that can harness the fixed route assurance necessary to unlock new land value appreciation that can be leveraged to contribute to construction and running costs whilst creating urban regeneration. The paper considers the niche for Trackless Trams in cities along with its potential for city shaping through the creation of urban re-development along corridors. The paper suggests that the adoption of Trackless Tram Systems is likely to grow rapidly as a genuine alternative to car and bus systems, supplementing and extending the niche occupied by Light Rail Transit (LRT). This appears to be feasible in any medium-sized or larger city, especially in emerging and developing economies, and case studies are outlined for Perth and Thimpu to illustrate its potential.展开更多
As an attractive transition approach,the altitude-hold transition is a special type of super-maneuvering and the vertical/horizontal flight mode transition that an agile aircraft conducts at fixed altitude.However,it ...As an attractive transition approach,the altitude-hold transition is a special type of super-maneuvering and the vertical/horizontal flight mode transition that an agile aircraft conducts at fixed altitude.However,it is still challenging to implement an autonomous control of the altitude-hold transition while the existing optimal transition planning methods cannot avoid an evident altitude change during the transition process.This paper proposes a corridor-based flight mode transition strategy and presents a successful flight demonstration of the altitude-hold transition on a small ducted-fan tail-sitter unmanned aerial vehicle.In the proposed corridor-based methodology,we model and analyze the transition corridor,concentrate on the dynamic characteristics of the altitude-hold transition,and emphasize that a valid transition trajectory should be governed by its transition corridor.The identified transition corridor reveals that for a given velocity trajectory,the solution for the corresponding trajectories of pitch angle and thrust is unique.Based on this,the transition trajectory generation problem is addressed simply on the velocity-acceleration plane.Furthermore,a proper flight control scheme is devised to track the generated transition trajectories.Finally,the effectiveness of the proposed method is verified through practical flight tests,in which the altitude change is less than 1.1 m during the entire transition course.展开更多
Increasing calls for zero-carbon cities invite transformative solutions for people and places within our cities around the world. Key to the transformation is cities and regions shifting in mobility away from fossil-f...Increasing calls for zero-carbon cities invite transformative solutions for people and places within our cities around the world. Key to the transformation is cities and regions shifting in mobility away from fossil-fuel based car-oriented solutions. The paper investigates a range of case studies where “tram-based boulevards” have been planned or implemented to provide such opportunities. The case studies share a common broader policy objective: to transform the car-oriented or car-saturated areas to an intensified urban template based on a critical presence of dedicated mid-tier transit infrastructure and active transport. “Trams”, or mid-tier, mid-capacity transit when combined with Transit oriented development (TOD) along whole corridors can provide transformative pathways towards zero-carbon outcomes as well as multiple, strong urban benefits. However, many successful or instructive examples of this practice from non-English speaking countries, particularly in Europe, are underdocumented in the international literature. The paper addresses this gap by investigating opportunities and challenges evident in a range of European case studies. These are explored for insight towards policy learning particularly in New World cities seeking to transform into a zero-carbon and more transit-oriented template: How can decision-makers avoid repeating the identified pitfalls, and instead focus on emulating the successful approaches and outcomes? We conclude the need for recognition of the inherent synergies between transport and land use settings in any endeavour, and their translation into policy priorities in both fields of planning. We also conclude the importance of decision makers proactively identifying and critically appraising specific opportunities for change, concerning funding, technology, public opinion, stakeholder alliances or market dynamics, and capitalising on them at suitable moments in time.展开更多
文摘The landlocked countries are the one without access to the sea and can be assimilate as countries around the world with a disadvantage of geography situation location. Chad and the Central African Republic are two of the 40 landlocked countries around the world that transport 80% of their goods by road and rail, and as much as almost more than 50% of their passengers through a transit country with a transit transport system which is crucial for their trade and exchanges. The study aims to introduce the importance to have a good and efficiency transport network infrastructure in Central Africa to facilitate the trade for the landlocked countries of Central Africa (Chad and the Central African Republic), member of CEMAC trade area and proposes some measures that can be adopt</span><span style="font-family:"">ed</span><span style="font-family:""> to improve their conditions and ameliorate the trade for those countries.
文摘Recent innovations in transport technology are now providing mobility that is cheaper, autonomous, electric, and with improved ride quality. While much of the world’s attention has been on how this can be applied to cars, there have been rapid adoption of these and other technologies in High Speed Rail and Metro Rail systems that run between and across cities. This paper shows how such innovations have now been applied to create the next generation of urban transit system called a Trackless Tram. Trackless Trams are effectively the same as traditional light rail except they run on rubber tyres avoiding disruption from construction for Light Rail, but they retain the electric propulsion (with batteries) and have high ride quality due to rail-type bogies, stabilization technologies and precision tracking from the autonomous optical guidance systems—with infrastructure costs reduced to as low as one tenth of a Light Rail system. As with Light Rail, a Trackless Tram System provides a rapid transit option that can harness the fixed route assurance necessary to unlock new land value appreciation that can be leveraged to contribute to construction and running costs whilst creating urban regeneration. The paper considers the niche for Trackless Trams in cities along with its potential for city shaping through the creation of urban re-development along corridors. The paper suggests that the adoption of Trackless Tram Systems is likely to grow rapidly as a genuine alternative to car and bus systems, supplementing and extending the niche occupied by Light Rail Transit (LRT). This appears to be feasible in any medium-sized or larger city, especially in emerging and developing economies, and case studies are outlined for Perth and Thimpu to illustrate its potential.
基金supported by Scientific Instruments Development Program of National Natural Science Foundation of China(No.61527810)the Fundamental Research Funds for the Central Universities,Chinathe Key Laboratory of Autonomous Systems and Networked Control,Ministry of Education and the Unmanned Aerial Vehicle Systems Engineering Technology Research Center of Guangdong(China)for supporting this research.
文摘As an attractive transition approach,the altitude-hold transition is a special type of super-maneuvering and the vertical/horizontal flight mode transition that an agile aircraft conducts at fixed altitude.However,it is still challenging to implement an autonomous control of the altitude-hold transition while the existing optimal transition planning methods cannot avoid an evident altitude change during the transition process.This paper proposes a corridor-based flight mode transition strategy and presents a successful flight demonstration of the altitude-hold transition on a small ducted-fan tail-sitter unmanned aerial vehicle.In the proposed corridor-based methodology,we model and analyze the transition corridor,concentrate on the dynamic characteristics of the altitude-hold transition,and emphasize that a valid transition trajectory should be governed by its transition corridor.The identified transition corridor reveals that for a given velocity trajectory,the solution for the corresponding trajectories of pitch angle and thrust is unique.Based on this,the transition trajectory generation problem is addressed simply on the velocity-acceleration plane.Furthermore,a proper flight control scheme is devised to track the generated transition trajectories.Finally,the effectiveness of the proposed method is verified through practical flight tests,in which the altitude change is less than 1.1 m during the entire transition course.
文摘Increasing calls for zero-carbon cities invite transformative solutions for people and places within our cities around the world. Key to the transformation is cities and regions shifting in mobility away from fossil-fuel based car-oriented solutions. The paper investigates a range of case studies where “tram-based boulevards” have been planned or implemented to provide such opportunities. The case studies share a common broader policy objective: to transform the car-oriented or car-saturated areas to an intensified urban template based on a critical presence of dedicated mid-tier transit infrastructure and active transport. “Trams”, or mid-tier, mid-capacity transit when combined with Transit oriented development (TOD) along whole corridors can provide transformative pathways towards zero-carbon outcomes as well as multiple, strong urban benefits. However, many successful or instructive examples of this practice from non-English speaking countries, particularly in Europe, are underdocumented in the international literature. The paper addresses this gap by investigating opportunities and challenges evident in a range of European case studies. These are explored for insight towards policy learning particularly in New World cities seeking to transform into a zero-carbon and more transit-oriented template: How can decision-makers avoid repeating the identified pitfalls, and instead focus on emulating the successful approaches and outcomes? We conclude the need for recognition of the inherent synergies between transport and land use settings in any endeavour, and their translation into policy priorities in both fields of planning. We also conclude the importance of decision makers proactively identifying and critically appraising specific opportunities for change, concerning funding, technology, public opinion, stakeholder alliances or market dynamics, and capitalising on them at suitable moments in time.
