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Landfills have been widely constructed all around the world in order to properly dispose municipal solid waste (MSW). Understanding geotechnical properties of MSW is essential for the design and operation of landfills. A comprehensive investigation of geotechnical properties of MSW at the largest landfill in China was conducted, including waste composition, unit weight, void ratio, water content, hydraulic conductivity, and shear behavior. A large-scale rigid-wall permeameter and a direct-shear apparatus were adopted to test the hydraulic conductivity and shear behavior of the MSW, respectively. The composition of the MSW varied with age. With the depth increasing from 0 to 16 m, the unit weight increased from 7.2 to 12.5 kN/m3, while the void ratio decreased from 2.5 to 1.76. The water content ranged between 30.0% and 68.9% but did not show a trend with depth. The hydraulic conductivity of the MSW ranged between 4.6 × 10−4 and 6.7 × 10−3 cm/s. It decreased as the dry unit weight increased and was sensitive to changes in dry unit weight in deeper layers. Displacement-hardening was observed during the whole shearing process and the shear strength increased with the normal stress, the displacement rate, and the unit weight. The friction angle and cohesion varied from (15.7°, 29.1 kPa) to (21.9°, 18.3 kPa) with depth increasing from 4 to 16 m. The shear strength of the MSW obtained in this study was lower than the reported values in other countries, which was caused by the less fibrous materials in the specimens in this study. The results in this study will provide guidance in the design and operation of the landfills in China. © 2016 Elsevier Ltd

Landfills have been widely constructed all around the world in order to properly dispose municipal solid waste (MSW). Understanding geotechnical properties of MSW is essential for the design and operation of landfills. A comprehensive investigation of geotechnical properties of MSW at the largest landfill in China was conducted, including waste composition, unit weight, void ratio, water content, hydraulic conductivity, and shear behavior. A large-scale rigid-wall permeameter and a direct-shear apparatus were adopted to test the hydraulic conductivity and shear behavior of the MSW, respectively. The composition of the MSW varied with age. With the depth increasing from 0 to 16 m, the unit weight increased from 7.2 to 12.5 kN/m3, while the void ratio decreased from 2.5 to 1.76. The water content ranged between 30.0% and 68.9% but did not show a trend with depth. The hydraulic conductivity of the MSW ranged between 4.6 × 10−4 and 6.7 × 10−3 cm/s. It decreased as the dry unit weight increased and was sensitive to changes in dry unit weight in deeper layers. Displacement-hardening was observed during the whole shearing process and the shear strength increased with the normal stress, the displacement rate, and the unit weight. The friction angle and cohesion varied from (15.7°, 29.1 kPa) to (21.9°, 18.3 kPa) with depth increasing from 4 to 16 m. The shear strength of the MSW obtained in this study was lower than the reported values in other countries, which was caused by the less fibrous materials in the specimens in this study. The results in this study will provide guidance in the design and operation of the landfills in China. © 2016 Elsevier Ltd

Landfills have been widely constructed all around the world in order to properly dispose municipal solid waste (MSW). Understanding geotechnical properties of MSW is essential for the design and operation of landfills. A comprehensive investigation of geotechnical properties of MSW at the largest landfill in China was conducted, including waste composition, unit weight, void ratio, water content, hydraulic conductivity, and shear behavior. A large-scale rigid-wall permeameter and a direct-shear apparatus were adopted to test the hydraulic conductivity and shear behavior of the MSW, respectively. The composition of the MSW varied with age. With the depth increasing from 0 to 16 m, the unit weight increased from 7.2 to 12.5 kN/m3, while the void ratio decreased from 2.5 to 1.76. The water content ranged between 30.0% and 68.9% but did not show a trend with depth. The hydraulic conductivity of the MSW ranged between 4.6 × 10−4 and 6.7 × 10−3 cm/s. It decreased as the dry unit weight increased and was sensitive to changes in dry unit weight in deeper layers. Displacement-hardening was observed during the whole shearing process and the shear strength increased with the normal stress, the displacement rate, and the unit weight. The friction angle and cohesion varied from (15.7°, 29.1 kPa) to (21.9°, 18.3 kPa) with depth increasing from 4 to 16 m. The shear strength of the MSW obtained in this study was lower than the reported values in other countries, which was caused by the less fibrous materials in the specimens in this study. The results in this study will provide guidance in the design and operation of the landfills in China. © 2016 Elsevier Ltd

Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the surface geology is firstly conducted to ascertain the source materials. The physical parameters of the loose materials such as size, location, and soil type are investigated. The volume, sediment concentration and resistance parameters for debris flows are subsequently evaluated and adopted as the input for the debris flow simulation. Numerical debris flow simulation is then conducted according to the established parameters. The maximum flow depth and maximum flow velocity are calculated by solving the continuity equation, the momentum equation and a friction slope equation. Based on the simulation results, a debris flow hazard map as a function of both the maximum flow depth and the maximum flow velocity is finally produced.

Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the surface geology is firstly conducted to ascertain the source materials. The physical parameters of the loose materials such as size, location, and soil type are investigated. The volume, sediment concentration and resistance parameters for debris flows are subsequently evaluated and adopted as the input for the debris flow simulation. Numerical debris flow simulation is then conducted according to the established parameters. The maximum flow depth and maximum flow velocity are calculated by solving the continuity equation, the momentum equation and a friction slope equation. Based on the simulation results, a debris flow hazard map as a function of both the maximum flow depth and the maximum flow velocity is finally produced.

Shallow slope failures are one of the most frequent geological hazards in mountainous areas, which pose great danger to people and properties in affected areas. This paper presents a cell-based platform for quantitative risk assessment for shallow slope failures at a regional scale. There are five components in this platform; namely, a digital terrain module, a spatial rainfall distribution module, a slope stability and reliability evaluation module, a movement prediction module, and a risk assessment module. The locations and volumes of the slope failures are estimated using the slope stability and reliability evaluation module. The movement prediction module is used to predict the potential movement traces of the detached material, which moves along the steepest path. The risks of the slope failures are finally assessed using the risk assessment module, which can be used as an indicator for early warning. The vulnerability of a person to slope failure is determined by the volume of slope failure and angle of reach. The platform is applied to a 164.5 km2 hilly terrain in the Wenchuan earthquake zone to test its performance in quantitative risk assessment for regional shallow slope failures. The platform evaluates the risks of shallow slope failures at a regional scale efficiently.

Shallow slope failures are one of the most frequent geological hazards in mountainous areas, which pose great danger to people and properties in affected areas. This paper presents a cell-based platform for quantitative risk assessment for shallow slope failures at a regional scale. There are five components in this platform; namely, a digital terrain module, a spatial rainfall distribution module, a slope stability and reliability evaluation module, a movement prediction module, and a risk assessment module. The locations and volumes of the slope failures are estimated using the slope stability and reliability evaluation module. The movement prediction module is used to predict the potential movement traces of the detached material, which moves along the steepest path. The risks of the slope failures are finally assessed using the risk assessment module, which can be used as an indicator for early warning. The vulnerability of a person to slope failure is determined by the volume of slope failure and angle of reach. The platform is applied to a 164.5 km2 hilly terrain in the Wenchuan earthquake zone to test its performance in quantitative risk assessment for regional shallow slope failures. The platform evaluates the risks of shallow slope failures at a regional scale efficiently.

Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the surface geology is firstly conducted to ascertain the source materials. The physical parameters of the loose materials such as size, location, and soil type are investigated. The volume, sediment concentration and resistance parameters for debris flows are subsequently evaluated and adopted as the input for the debris flow simulation. Numerical debris flow simulation is then conducted according to the established parameters. The maximum flow depth and maximum flow velocity are calculated by solving the continuity equation, the momentum equation and a friction slope equation. Based on the simulation results, a debris flow hazard map as a function of both the maximum flow depth and the maximum flow velocity is finally produced.

Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the surface geology is firstly conducted to ascertain the source materials. The physical parameters of the loose materials such as size, location, and soil type are investigated. The volume, sediment concentration and resistance parameters for debris flows are subsequently evaluated and adopted as the input for the debris flow simulation. Numerical debris flow simulation is then conducted according to the established parameters. The maximum flow depth and maximum flow velocity are calculated by solving the continuity equation, the momentum equation and a friction slope equation. Based on the simulation results, a debris flow hazard map as a function of both the maximum flow depth and the maximum flow velocity is finally produced.

Shallow slope failures are one of the most frequent geological hazards in mountainous areas, which pose great danger to people and properties in affected areas. This paper presents a cell-based platform for quantitative risk assessment for shallow slope failures at a regional scale. There are five components in this platform; namely, a digital terrain module, a spatial rainfall distribution module, a slope stability and reliability evaluation module, a movement prediction module, and a risk assessment module. The locations and volumes of the slope failures are estimated using the slope stability and reliability evaluation module. The movement prediction module is used to predict the potential movement traces of the detached material, which moves along the steepest path. The risks of the slope failures are finally assessed using the risk assessment module, which can be used as an indicator for early warning. The vulnerability of a person to slope failure is determined by the volume of slope failure and angle of reach. The platform is applied to a 164.5 km2 hilly terrain in the Wenchuan earthquake zone to test its performance in quantitative risk assessment for regional shallow slope failures. The platform evaluates the risks of shallow slope failures at a regional scale efficiently.

Shallow slope failures are one of the most frequent geological hazards in mountainous areas, which pose great danger to people and properties in affected areas. This paper presents a cell-based platform for quantitative risk assessment for shallow slope failures at a regional scale. There are five components in this platform; namely, a digital terrain module, a spatial rainfall distribution module, a slope stability and reliability evaluation module, a movement prediction module, and a risk assessment module. The locations and volumes of the slope failures are estimated using the slope stability and reliability evaluation module. The movement prediction module is used to predict the potential movement traces of the detached material, which moves along the steepest path. The risks of the slope failures are finally assessed using the risk assessment module, which can be used as an indicator for early warning. The vulnerability of a person to slope failure is determined by the volume of slope failure and angle of reach. The platform is applied to a 164.5 km2 hilly terrain in the Wenchuan earthquake zone to test its performance in quantitative risk assessment for regional shallow slope failures. The platform evaluates the risks of shallow slope failures at a regional scale efficiently.

Due to hilly terrain and frequent heavy rainstorms, debris flow is one of the most common and catastrophic hazards in Hong Kong. To mitigate the debris flow risk, prediction of the magnitude and consequence of debris flow is essential. The objective of this paper is to simulate debris flow hazards in a study area in Hong Kong. Assessment of the surface geology is firstly conducted to ascertain the source materials. The physical parameters of the loose materials such as size, location, and soil type are investigated. The volume, sediment concentration and resistance parameters for debris flows are subsequently evaluated and adopted as the input for the debris flow simulation. Numerical debris flow simulation is then conducted according to the established parameters. The maximum flow depth and maximum flow velocity are calculated by solving the continuity equation, the momentum equation and a friction slope equation. Based on the simulation results, a debris flow hazard map as a function of both the maximum flow depth and the maximum flow velocity is finally produced.

The 12 May 2008 Wenchuan earthquake in China triggered numerous landslides. Loose landslide materials can easily evolve into deadly debris flows during wet seasons. During the period from 2008 to 2011, three separate large-scale debris flows occurred in the Pubugou Ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported. Approximately 1.76 × 106 m3 of sediment was deposited during these three events. This paper aims to (i) analyze the movements of solid materials during the repeated debris flows, (ii) discuss the evolution of the initiation mechanisms of these debris flows, and (iii) evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials. To achieve the above research objectives, timely field investigations were undertaken in the past 5 years after each of these debris flow events. Satellite images were used to delineate the boundaries of the initiation areas, the transportation channels, and the deposition zones of these debris flows. With the occurrence of the repeated debris flows, the hill slope deposits gradually evolved into channel deposits and the solid materials in the channels moved toward the gully mouth. Hence, channelized flows gradually became dominant. The debris fan materials of the repeated debris flows became coarser and coarser over time. The three debris flows were all characterized by coarse boulder fronts.

The 12 May 2008 Wenchuan earthquake in China triggered numerous landslides. Loose landslide materials can easily evolve into deadly debris flows during wet seasons. During the period from 2008 to 2011, three separate large-scale debris flows occurred in the Pubugou Ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported. Approximately 1.76 × 106 m3 of sediment was deposited during these three events. This paper aims to (i) analyze the movements of solid materials during the repeated debris flows, (ii) discuss the evolution of the initiation mechanisms of these debris flows, and (iii) evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials. To achieve the above research objectives, timely field investigations were undertaken in the past 5 years after each of these debris flow events. Satellite images were used to delineate the boundaries of the initiation areas, the transportation channels, and the deposition zones of these debris flows. With the occurrence of the repeated debris flows, the hill slope deposits gradually evolved into channel deposits and the solid materials in the channels moved toward the gully mouth. Hence, channelized flows gradually became dominant. The debris fan materials of the repeated debris flows became coarser and coarser over time. The three debris flows were all characterized by coarse boulder fronts.

The 12 May 2008 Wenchuan earthquake in China triggered numerous landslides. Loose landslide materials can easily evolve into deadly debris flows during wet seasons. During the period from 2008 to 2011, three separate large-scale debris flows occurred in the Pubugou Ravine near the epicentre of the earthquake that were among the largest repeated debris flows ever reported. Approximately 1.76 × 106 m3 of sediment was deposited during these three events. This paper aims to (i) analyze the movements of solid materials during the repeated debris flows, (ii) discuss the evolution of the initiation mechanisms of these debris flows, and (iii) evaluate the changing depositional morphology of the debris flow fans and examine the particle sizes of the debris flow materials. To achieve the above research objectives, timely field investigations were undertaken in the past 5 years after each of these debris flow events. Satellite images were used to delineate the boundaries of the initiation areas, the transportation channels, and the deposition zones of these debris flows. With the occurrence of the repeated debris flows, the hill slope deposits gradually evolved into channel deposits and the solid materials in the channels moved toward the gully mouth. Hence, channelized flows gradually became dominant. The debris fan materials of the repeated debris flows became coarser and coarser over time. The three debris flows were all characterized by coarse boulder fronts.

To solve the problem of audio-video synchronous coding effectively, an embedding scheme is proposed. This scheme applies the quarter-pixel motion search during the motion estimation in H.264. At the transmitter terminal, according to the mapping rule between the binary audio bits and the search points, the audio bits are embedded into the video signal by modulating the best search point in the quarter-pixel motion estimation. Then the synchronous coding is applied to the hybrid signals. At the receiver terminal, the audio information bits are extracted from the video stream according to the embedding rule. Then the audio and video signals are reconstructed respectively. Experiment results show that the proposed scheme can achieve audio-video synchronous coding with low embedding cost and good performance in quality of video and audio signals.

To solve the problem of audio-video synchronous coding effectively, an embedding scheme is proposed. This scheme applies the quarter-pixel motion search during the motion estimation in H.264. At the transmitter terminal, according to the mapping rule between the binary audio bits and the search points, the audio bits are embedded into the video signal by modulating the best search point in the quarter-pixel motion estimation. Then the synchronous coding is applied to the hybrid signals. At the receiver terminal, the audio information bits are extracted from the video stream according to the embedding rule. Then the audio and video signals are reconstructed respectively. Experiment results show that the proposed scheme can achieve audio-video synchronous coding with low embedding cost and good performance in quality of video and audio signals.

A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 x 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

A stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, which determines delivery volumes to the customers that the depot serves in each period, and vehicle routes to deliver the volumes. This paper aims to solve a large scale multi-period SIRP with split delivery (SIRPSD) where a customer’s delivery in each period can be split and satisfied by multiple vehicle routes if necessary. This paper considers SIRPSD under the multi-criteria of the total inventory and transportation costs, and the service levels of customers. The total inventory and transportation cost is considered as the objective of the problem to minimize, while the service levels of the warehouses and the customers are satisfied by some imposed constraints and can be adjusted according to practical requests. In order to tackle the SIRPSD with notorious computational complexity, we first propose an approximate model, which significantly reduces the number of decision variables compared to its corresponding exact model. We then develop a hybrid approach that combines the linearization of nonlinear constraints, the decomposition of the model into sub-models with Lagrangian relaxation, and a partial linearization approach for a sub model. A near optimal solution of the model found by the approach is used to construct a near optimal solution of the SIRPSD. Randomly generated instances of the problem with up to 200 customers and 5 periods and about 400 thousands decision variables where half of them are integer are examined by numerical experiments. Our approach can obtain high quality near optimal solutions within a reasonable amount of computation time on an ordinary PC.

A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 x 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

A Geographic Information System (GIS)-based quantitative risk assessment methodology was adopted to evaluate the risks of loose deposits formed by the 2008 Wenchuan earthquake along a highway near the epicenter. A total of 305 loose deposits with a total volume of 4.0 x 107 m3 has been identified. A physical model was used to determine the failure probability of these loose deposits under six rainfall scenarios, assuming the loose deposits as infinite slopes. The calculated probability of rain-induced slope failures is verified by the recorded landslides at the same site during a storm in 2010. Seventy-nine out of the 112 rain-induced loose deposit failures are predicted by the reliability analysis, with an accuracy of 71%. The results of reliability analysis and information on the consequence of these rain-induced landslides enable the estimation of the annual societal and individual risks of the loose deposits. Under the rainfall scenarios of 30 mm/12 h and 70 mm/12 h, the estimated annual societal risks reach 8.8 and 7.5, respectively, and the individual risks reach 0.05 and 0.04, respectively, which are very high compared with present risk acceptance criteria. The preliminary assessment provides a benchmark for studying the long-term risks of these loose deposits and engineering decision.

A stochastic inventory routing problem (SIRP) is typically the combination of stochastic inventory control problems and NP-hard vehicle routing problems, for a depot to determine delivery volumes to its customers in each period, and vehicle routes to distribute the delivery volumes. This paper aims to solve a large scale multi-period SIRP with split delivery (SIRPSD) where a customer’s delivery in each period can be split and satisfied by multiple vehicles if necessary. The objective of the problem is to minimize the total inventory and transportation cost while some constraints are given to satisfy other criteria, such as the service level to limit the stockout probability at each customer and the service level to limit the overfilling probability of the warehouse of each customer. In order to tackle the SIRPSD with notorious computational complexity, we propose for it an approximate model, which significantly reduces the number of decision variables compared to its corresponding exact model. We develop a hybrid approach that combines the linearization of nonlinear constraints, the decomposition of the model into sub-models with Lagrangian relaxation, and a partial linearization approach for a sub model. A near optimal solution of the model can be found by the approach, and then be used to construct a near optimal solution of the SIRPSD. Numerical examples show that, for an instance of the problem with 200 customers and 5 periods that contains about 400 thousands decision variables where half of them are integer, our approach can obtain high quality near optimal solutions with a reasonable computational time on an ordinary PC.