Gotowa bibliografia na temat „Over-constrained temporal problems”

The paper introduces a new, intrinsically discrete, path planning and collision-avoidance problem, with multiple robots and multiple goals. The issue arises in the operation of the novel Swing and Dock (SaD) locomotion for a material handling system. Its agents traverse a base grid by sequences of rotations (swings) around fixed pins. Each agent must visit an array of goal positions in minimal time while avoiding collisions. The corresponding off-line path-planning problem is NP-hard. We model the system by an extended temporal graph and introduce two integer linear programming (ILP) formulations for the minimization of the makespan, with decision variables on the nodes and the edges, respectively. Both optimizations are constrained and favor idling over detours to reduce mechanical wear. The ILP formulations, tailored to the SaD system, are general enough to be applicable for many other single- and multi-agent problems over discretized networks. We have implemented the ILPs with a gurobi solver. Computational results demonstrate and compare the effectiveness of the two formulations.

One can recover the motion of an observer in a static environment directly from first derivatives (spatial and temporal) of image brightness, accumulated over a large part of the image. There is no need to extract features and to determine correspondences between features in successive frames. This is fortunate, since the correspondence problem in the case of motion vision is even harder than it is for binocular stereo, where matching features have to lie on corresponding epipolar lines. Motion vision—at least short-range motion vision—should be easier than binocular stereo, not harder. In the case of rigid body motion there is also no need to first estimate the optical flow, since it is so highly constrained.

Abstract This paper offers an integrative behavioral-based physics-inspired approach to model and control traffic congestion in an efficient manner While existing physics-based approaches commonly assign density and traffic flow states with the Fundamental Diagram, this paper specifies the flow-density relation using past traffic behavior (intent) recorded over a time sliding window with constant horizon length. With this approach, traffic coordination trends can be consistently learned and incorporated into traffic planning. This is integrated with mass conservation law (continuity) to model traffic coordination as a probabilistic process and obtain traffic feasibility conditions using linear temporal logic. By spatial discretization of a network of inter-connected roads (NOIR), the NOIR is represented by a graph with inlet boundary nodes, outlet boundary nodes, and interior nodes. The paper offers a boundary control approach to manage congestion through the inlet boundary nodes. More specifically, model predictive control (MPC) is applied to control traffic congestion through the boundary of the traffic network. Therefore, the optimal boundary in flow is assigned as the solution of a constrained quadratic programming problem with equality and inequality constrained. The simulation results shows that the proposed MPC boundary controller can successfully control the traffic through the inlet boundary nodes where traffic reaches the steady state condition.

This paper presents an implementation of a novel dynamic formulation on multibody systems involving closed loops. The formulation allows the treatment of time, appearing within the equations of motion, as a variable in much the same manner as having been done by the finite element community on the spatial coordinates. As a consequence, the resulting equations appear together in a single all-encompassing set of algebraic equations which may be solved simultaneously, yielding the system state for all times within the time interval considered. The approach conceivably allows the problem to be parallelized over both space and time, resulting in a far greater level of coarse grain parallelization. As the Stewart Platform is a heavily constrained system with its spatial domain being much smaller than the temporal domain of simulation, it will serve as a perfect example to test the implication of this method. Simulation results obtained from traditional dynamic techniques will be used for verification purposes.

The formal synthesis of automated or autonomous agents has elicited strong interest from the artificial intelligence community in recent years. This problem space broadly entails the derivation of decision-making policies for agents acting in an environment such that a formal specification of behavior is satisfied. Popular formalisms for such specifications include the quintessential Linear Temporal Logic (LTL) and Computation Tree Logic (CTL) which reason over infinite sequences and trees, respectively, of states. However, the related and relevant problem of reasoning over the frequency with which states are visited infinitely and enforcing behavioral specifications on the same has received little attention. That problem, known as Steady-State Policy Synthesis (SSPS) or steady-state control, is the focus of this paper. Prior related work has been mostly confined to unichain Markov Decision Processes (MDPs), while a tractable solution to the general multichain setting heretofore remains elusive. In this paper, we provide a solution to the latter within the context of multichain MDPs over a class of policies that account for all possible transitions in the given MDP. The solution policy is derived from a novel linear program (LP) that encodes constraints on the limiting distributions of the Markov chain induced by said policy. We establish a one-to-one correspondence between the feasible solutions of the LP and the stationary distributions of the induced Markov chains. The derived policy is shown to maximize the reward among the constrained class of stationary policies and to satisfy the specification constraints even when it does not exercise all possible transitions.

The rapid urban development in the Hurghada area since the 1980s has dramatically enhanced the potential impact of human activities. To inventory and monitor this urban development effectively, remote sensing provides a viable source of data from which updated land cover information can be extracted efficiently and cheaply. In this study, data from three satellite datasets, Landsat Thematic Mapper (Landsat 5 TM), Landsat Enhanced Thematic Mapper Plus (Landsat 7 ETM+) and Terra/Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), acquired during 1987, 2000 and 2005, respectively, were used to detect and evaluate Hurghada's urban expansion. Five change detection techniques were tested to detect areas of change. The techniques considered were image differencing, image ratioing, image overlay, multidate principal component analysis (PCA) and post-classification comparison. The post-classification comparison was found to be the most accurate procedure and produced three land use/land cover (LULC) maps of the years 1987, 2000 and 2005 with overall accuracies of 87.8%, 88.9% and 92.0%, respectively. The urban expansion analysis revealed that the built-up area has expanded by 40 km2 in 18 years (1987–2005). In addition, 4.5 km2 of landfill/sedimentation was added to the sea as a result of the coastal urban development and tourist activities. The booming coastal tourism and population pressure were considered to be the main factors driving this expansion, and some natural and artificial constraints constrained the physical shape of the city. The expansion is represented by urban fringe development, linear, infill and isolated models. Topography, lithology and structures were also analysed as possible factors that influenced the expansion. The understanding of the spatial and temporal dynamics of Hurghada's urban expansion is the cornerstone for formulating a view about the future urban uses and for making the best use of the limited resources that are available [1]. A Landsat 5 Thematic Mapper (TM) image of 1987 and a Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image of 2000 were used to examine changes in land use/land cover (LULC) around Hurghada, Egypt, and changes in the composition of coral reefs offshore. Prior to coral reef bottom type classification, the radiance values were transformed to depth invariant bottom indices to reduce the effect of the water column. Subsequently, a multi component change detection procedure was applied to these indices to define changes. Preliminary results showed significant changes in LULC during the period 1987–2000 as well as changes in coral reef composition. Direct impacts along the coastline were clearly shown, but it was more difficult to link offshore changes in coral reef composition to indirect impacts of the changing LULC. Further research is needed to explore the effects of the different image processing steps, and to discover possible links between indirect impacts of LULC changes and changes in the coral reef composition [2]. Knowledge and detecting impacts of human activities on the coastal ecosystem is an essential management requirement and also very important for future and proper planning of coastal areas. Moreover, documentation of these impacts can help in increasing public awareness about side effects of unsustainable practices. Analysis of multidate remote sensing data can be used as an effective tool in environmental impact assessment (EIA). Being synoptic and frequent in coverage, multidate data from Landsat and other satellites provide a reference record and bird’s eye viewing to the environmental situation of the coastal ecosystem and the associated habitats. Furthermore, integration of satellite data with field observations and background information can help in decision if a certain activity has caused deterioration to a specific habitat or not. The present paper is an attempt to utilize remote sensing data for assessment impacts of some human activities on the major sensitive habitats of the north western Egyptian Red Sea coastal zone, definitely between Ras Gemsha and Safaga. Through multidate change analysis of Landsat data (TM & ETM+ sensors), it was possible to depict some of the human infringements in the area and to provide, in some cases, exclusive evidences for the damaging effect of some developmental activities [3]. The coastline of Hurghada has experienced considerable environmental stress from tourist and residential recreational activities. Uncontrolled tourist development has already caused substantial damage to inshore reefs and imbalance in the hydrodynamic pattern of the coastal sediments. The objective of this paper is to investigate environmental changes using multitemporal, multispectral satellite data to identify changes at Hurghada caused by anthropogenic influences. Major detected changes include resort beaches, protection structures and landfill areas; these changes are mainly due to human intervention. Two Landsat Thematic Mapper (TM) images acquired in 1984 and 1997 are used for this analysis. The landfill areas formed during this period are calculated at about 2.15 Km2 . Whilst landfill creates new inexpensive land and improves access to the sea for tourists, it is the cause of environmental problems. In addition, land-use/land-cover and beach changes are determined over the 13-year period [4]. The Red Sea coastal zone is characterized by its sensitive, fragile, unique natural resources and habitats. In the Hurghada coastal region, major changes in the tourism industry have taken place in the last few decades. The detection of environmental changes, in a selected site of the Red Sea coastal zone, will be helpful to protect and develop this coastal environment. A methodology for separating natural and man-made changes in satellite images was developed. It was based on the following assumptions: (1) slow changes, which occur within the range of the class reflectance, represent a natural change rather than an anthropogenic one; (2) natural changes tend to be in the same land-use/land-cover class in each date, i.e. slow changes in the reflectance, not leading to changes in the type of land-use/land-cover class from the master image to the destination one; and (3) rapid changes in the reflectance of the Earth's objects are usually related to anthropogenic activities. This technique is used to identify and assess changes along the coast of Hurghada and Ras Abu Soma, the Red Sea. Results indicate serious human impacts and the necessity for control measures and monitoring. Recommendations are presented [5]. The rapid urban development of the Hurghada area began in early 1980 to build villages and huge tourist resorts and this has continued urban development and subsequent land filling and dredging of the shoreline and the destruction of coral so far. These coastal developments have led to an increase in shoreline land filling and dredging. Despite all the environmental laws of the organization to reduce infringement on the shoreline, the abuses are still ongoing. Change detection analysis using remote sensing is a very good tool to monitor the changes condition in urban development and shoreline. Four sensors was used in this study, three of them are, Landsat Multispectral Scanner (Landsat 1 MSS), Landsat Thematic Mapper (Landsat 5 TM), Landsat Enhanced Thematic Mapper Plus (Landsat 7 ETM+) and the another one is SPOT XS 4 (Originally Système Probatoire de l’Observation de la Terre), acquired during 1972, 1984, 1992, 2004 and 2011, respectively, were used to detect and evaluate Hurghada’s urban expansion and shoreline changes. After the images have been geometrically, radio-metrically and atmospherically corrected using ENVI 5.0 software, the digital number was transformed to the reflectance values and the images were ready to change detection process with the integration of geographic information system using Arc GIS 10 software. The results show that changes during the 39 years of the shoreline is 6.29 km2, (5.65 km2 accretion and 0.64 km2 erosion) and urban development is 16.47 km2 the road network is the 8.738 km2.

The rapid urban development in the Hurghada area since the 1980s has dramatically enhanced the potential impact of human activities. To inventory and monitor this urban development effectively, remote sensing provides a viable source of data from which updated land cover information can be extracted efficiently and cheaply. In this study, data from three satellite datasets, Landsat Thematic Mapper (Landsat 5 TM), Landsat Enhanced Thematic Mapper Plus (Landsat 7 ETM+) and Terra/Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER), acquired during 1987, 2000 and 2005, respectively, were used to detect and evaluate Hurghada's urban expansion. Five change detection techniques were tested to detect areas of change. The techniques considered were image differencing, image ratioing, image overlay, multidate principal component analysis (PCA) and post-classification comparison. The post-classification comparison was found to be the most accurate procedure and produced three land use/land cover (LULC) maps of the years 1987, 2000 and 2005 with overall accuracies of 87.8%, 88.9% and 92.0%, respectively. The urban expansion analysis revealed that the built-up area has expanded by 40 km2 in 18 years (1987–2005). In addition, 4.5 km2 of landfill/sedimentation was added to the sea as a result of the coastal urban development and tourist activities. The booming coastal tourism and population pressure were considered to be the main factors driving this expansion, and some natural and artificial constraints constrained the physical shape of the city. The expansion is represented by urban fringe development, linear, infill and isolated models. Topography, lithology and structures were also analysed as possible factors that influenced the expansion. The understanding of the spatial and temporal dynamics of Hurghada's urban expansion is the cornerstone for formulating a view about the future urban uses and for making the best use of the limited resources that are available [1]. A Landsat 5 Thematic Mapper (TM) image of 1987 and a Landsat 7 Enhanced Thematic Mapper Plus (ETM+) image of 2000 were used to examine changes in land use/land cover (LULC) around Hurghada, Egypt, and changes in the composition of coral reefs offshore. Prior to coral reef bottom type classification, the radiance values were transformed to depth invariant bottom indices to reduce the effect of the water column. Subsequently, a multi component change detection procedure was applied to these indices to define changes. Preliminary results showed significant changes in LULC during the period 1987–2000 as well as changes in coral reef composition. Direct impacts along the coastline were clearly shown, but it was more difficult to link offshore changes in coral reef composition to indirect impacts of the changing LULC. Further research is needed to explore the effects of the different image processing steps, and to discover possible links between indirect impacts of LULC changes and changes in the coral reef composition [2]. Knowledge and detecting impacts of human activities on the coastal ecosystem is an essential management requirement and also very important for future and proper planning of coastal areas. Moreover, documentation of these impacts can help in increasing public awareness about side effects of unsustainable practices. Analysis of multidate remote sensing data can be used as an effective tool in environmental impact assessment (EIA). Being synoptic and frequent in coverage, multidate data from Landsat and other satellites provide a reference record and bird’s eye viewing to the environmental situation of the coastal ecosystem and the associated habitats. Furthermore, integration of satellite data with field observations and background information can help in decision if a certain activity has caused deterioration to a specific habitat or not. The present paper is an attempt to utilize remote sensing data for assessment impacts of some human activities on the major sensitive habitats of the north western Egyptian Red Sea coastal zone, definitely between Ras Gemsha and Safaga. Through multidate change analysis of Landsat data (TM & ETM+ sensors), it was possible to depict some of the human infringements in the area and to provide, in some cases, exclusive evidences for the damaging effect of some developmental activities [3]. The coastline of Hurghada has experienced considerable environmental stress from tourist and residential recreational activities. Uncontrolled tourist development has already caused substantial damage to inshore reefs and imbalance in the hydrodynamic pattern of the coastal sediments. The objective of this paper is to investigate environmental changes using multitemporal, multispectral satellite data to identify changes at Hurghada caused by anthropogenic influences. Major detected changes include resort beaches, protection structures and landfill areas; these changes are mainly due to human intervention. Two Landsat Thematic Mapper (TM) images acquired in 1984 and 1997 are used for this analysis. The landfill areas formed during this period are calculated at about 2.15 Km2 . Whilst landfill creates new inexpensive land and improves access to the sea for tourists, it is the cause of environmental problems. In addition, land-use/land-cover and beach changes are determined over the 13-year period [4]. The Red Sea coastal zone is characterized by its sensitive, fragile, unique natural resources and habitats. In the Hurghada coastal region, major changes in the tourism industry have taken place in the last few decades. The detection of environmental changes, in a selected site of the Red Sea coastal zone, will be helpful to protect and develop this coastal environment. A methodology for separating natural and man-made changes in satellite images was developed. It was based on the following assumptions: (1) slow changes, which occur within the range of the class reflectance, represent a natural change rather than an anthropogenic one; (2) natural changes tend to be in the same land-use/land-cover class in each date, i.e. slow changes in the reflectance, not leading to changes in the type of land-use/land-cover class from the master image to the destination one; and (3) rapid changes in the reflectance of the Earth's objects are usually related to anthropogenic activities. This technique is used to identify and assess changes along the coast of Hurghada and Ras Abu Soma, the Red Sea. Results indicate serious human impacts and the necessity for control measures and monitoring. Recommendations are presented [5]. The rapid urban development of the Hurghada area began in early 1980 to build villages and huge tourist resorts and this has continued urban development and subsequent land filling and dredging of the shoreline and the destruction of coral so far. These coastal developments have led to an increase in shoreline land filling and dredging. Despite all the environmental laws of the organization to reduce infringement on the shoreline, the abuses are still ongoing. Change detection analysis using remote sensing is a very good tool to monitor the changes condition in urban development and shoreline. Four sensors was used in this study, three of them are, Landsat Multispectral Scanner (Landsat 1 MSS), Landsat Thematic Mapper (Landsat 5 TM), Landsat Enhanced Thematic Mapper Plus (Landsat 7 ETM+) and the another one is SPOT XS 4 (Originally Système Probatoire de l’Observation de la Terre), acquired during 1972, 1984, 1992, 2004 and 2011, respectively, were used to detect and evaluate Hurghada’s urban expansion and shoreline changes. After the images have been geometrically, radio-metrically and atmospherically corrected using ENVI 5.0 software, the digital number was transformed to the reflectance values and the images were ready to change detection process with the integration of geographic information system using Arc GIS 10 software. The results show that changes during the 39 years of the shoreline is 6.29 km2, (5.65 km2 accretion and 0.64 km2 erosion) and urban development is 16.47 km2 the road network is the 8.738 km2.