Multiple Time Windows Research Articles

A Study for Solving Multi-Depot Dial-a-Ride Problem Considering Soft Time Window

Dial-a-ride is the most widely available transit service for disabled persons or seniors in the United States and Europe. This paper studies a static dial-a-ride problem considering multiple depots, heterogeneous vehicles, and soft time windows. In this paper, we apply a heuristic based on clustering first-routing second(HCR) to a real-world large dial-a-ride problem from Maryland Transit Administration(MTA). MTA`s real operation is compared with the results of developed heuristic for 24 cases. The objective function of the proposed model is to minimize the total cost composed of the service provider`s cost and the customers` inconvenience cost. For the comparison, the objective function values of HCR do not include waiting cost, delay cost, and excess ride cost. The objective function values from HCR are better than those from MTA`s operation for all cases. This result shows that our heuristic method can make the real operation better and more efficient.

Self-adaptive large neighborhood search algorithm for parallel machine scheduling problems

A self-adaptive large neighborhood search method for scheduling n jobs on m non-identical parallel machines with multiple time windows is presented. The problems' another feature lies in oversubscription, namely not all jobs can be scheduled within specified scheduling horizons due to the limited machine capacity. The objective is thus to maximize the overall profits of processed jobs while respecting machine constraints. A first-in-first-out heuristic is applied to find an initial solution, and then a large neighborhood search procedure is employed to relax and re-optimize cumbersome solutions. A machine learning mechanism is also introduced to converge on the most efficient neighborhoods for the problem. Extensive computational results are presented based on data from an application involving the daily observation scheduling of a fleet of earth observing satellites. The method rapidly solves most problem instances to optimal or near optimal and shows a robust performance in sensitive analysis.

A three-phase hybrid heuristic for time dependent vehicle routing problem with multiple time windows

A three-phase hybrid heuristic for time dependent vehicle routing problem with multiple time windows

Foreword

Wireless rechargeable sensor networks (WRSN) exploit wireless energy transfer techniques to replenish sensor batteries using chargers. Compared to non-rechargeable networks, WRSNs offer controllable and predictable energy replenishment and prolong the network lifetime. While previous mobile charging protocols in WRSNs consider multi-node energy transfer or the use of several chargers, in this work, we propose combining the two approaches. Our solution leverages simultaneous energy transfer to multiple nodes, with the aim of maximizing the number of nodes that are charged at each stop to reduce the charging delay. Moreover, it considers multiple chargers to serve more requesting nodes, which is expected to limit the number of node failures. Furthermore, we guarantee that there is no aggregated electromagnetic radiation (EMR), which can occur when two nearby chargers are simultaneously charging. This has not yet been considered in a mobile environment. To address these challenges, we introduce a new clustering algorithm to group demanding nodes, and we compute charging tours by iteratively solving a Traveling Salesman Problem with Multiple Time Windows problem (TSPMTW). The simulation results demonstrate that our approach reduces node failures in dynamic networks.

Spatio-temporal location modeling in a 3D indoor environment: the case of AEDs as emergency medical devices

This research innovatively extends optimal emergency facility location models to the interior space of multistory buildings with an integrated spatial-temporal framework. We present the case of deployed emergency medical devices known as automated external defibrillators (AEDs), which serve to treat sudden cardiac arrest on-site within the first few critical minutes of the event. AEDs have become a critical element of basic life support services in many public buildings. The proposed framework is based on the concept of discrete time windows to capture the time-dependence of potential demand and stochastically model the detection time component of impedance as a function of space–time distribution of demand. Different optimization objectives minimizing sudden cardiac arrest outcome consequences (e.g., brain damage or death) as a function of suffering time are formulated and solved. The first model is the multiple-time-window maximal covering location problem model which optimizes the placement of AEDs by maximizing the covered demand over all time periods. The second is the multiple-time-window p-Median model which places AEDs to maximize the expected value of prevented death or permanent brain impairment in case of defibrillation treatment over multiple time windows. Both models are implemented through tight coupling of commercial geographic information system software and a linear programming solver. The models are novel in two primary respects, namely location modeling in 3D microscale spaces and the integration of spatial and temporal considerations. Innovative visualization techniques for AED indoor location and coverage are also presented.

Scheduling Deliveries with Backhauls in Thailand's Cement Industry

The problem of truckload delivery with backhaul scheduling was formulated, and a methodology for ant colony optimization that was developed for a related problem, the problem of vehicle routing with backhaul and time windows, was adapted for the solution of the truckload delivery problem. The problem of truckload delivery with backhaul scheduling differs from the problem of vehicle routing with backhaul and time windows in that shipments are in units of truckloads, multiple time windows in multiple days are available for delivery to customers, limited space for servicing customers is available, and multiple visits to each customer may be required. The problem is motivated by a real-world application arising at a leading cement producer in Thailand. Experts at the cement production plant assign vehicles to cement customers and lignite mines on the basis of manual computations and experience. Mathematical and computational frameworks are provided for modeling and solving this real-world application.

Rupture at the flank of the subducted Gagua ridge: The 18 December 2001 earthquake (Mw 6.8) offshore eastern Taiwan

The southern Ryukyus represents an area where different tectonic stress regimes result in high seismicity and increased seismic hazard for nearby areas such as Taiwan. On 18 December 2001 at 04:03 (GMT) a strong earthquake (Mw 6.8) occurred in the forearc area of the southern Ryukyu subduction zone. Revised moment tensor solutions published by GCMT and BATS groups show a normal faulting mechanism with some strike-slip component and also point to a shallow focal depth (∼12 km). We use arrival times picked at both Taiwanese and Japanese stations along with a 3D geo-realistic a priori velocity model in order to obtain accurate absolute locations for the mainshock and 153 of its aftershocks. Locations are derived by using the Maximum intersection (MAXI) algorithm which has been used in many previous seismicity studies in the southern Ryukyus. These improved locations indicate that the mainshock was caused by the failure of a NE–SW oriented fault that extends from the edge of the Nanao forearc sedimentary basin to the Ryukyu arc basement. Far-field P and SH waveforms of the mainshock recorded at stations surrounding the source and at distances 30–100°, were inverted for the purpose of investigating its rupture process. A non-negative least-squares inversion technique utilizing multiple time windows was used to derive the spatio-temporal slip distribution. The preferred slip distribution model shows that there is one large area of high slip (∼0.9 m) at 5–15 km depth that essentially represents the crystalline rocks of the Ryukyu arc basement. Another smaller area with lower slip (∼0.4 m) extends at 10–15 km depth beneath the Nanao basin. Most aftershocks are located in areas of low slip (<0.4 m) filling the regions of slip deficit. It is likely that the 18 December 2001 earthquake was caused by a stress field interaction generated by the oblique subduction of the Gagua ridge and the gravitational forces acting at its landward flank.

Multivariate and multiscale dependence in the global climate system revealed through complex networks

A systematic characterization of multivariate dependence at multiple spatio-temporal scales is critical to understanding climate system dynamics and improving predictive ability from models and data. However, dependence structures in climate are complex due to nonlinear dynamical generating processes, long-range spatial and long-memory temporal relationships, as well as low-frequency variability. Here we utilize complex networks to explore dependence in climate data. Specifically, networks constructed from reanalysis-based atmospheric variables over oceans and partitioned with community detection methods demonstrate the potential to capture regional and global dependence structures within and among climate variables. Proximity-based dependence as well as long-range spatial relationships are examined along with their evolution over time, yielding new insights on ocean meteorology. The tools are implicitly validated by confirming conceptual understanding about aggregate correlations and teleconnections. Our results also suggest a close similarity of observed dependence patterns in relative humidity and horizontal wind speed over oceans. In addition, updraft velocity, which relates to convective activity over the oceans, exhibits short spatiotemporal decorrelation scales but long-range dependence over time. The multivariate and multi-scale dependence patterns broadly persist over multiple time windows. Our findings motivate further investigations of dependence structures among observations, reanalysis and model-simulated data to enhance process understanding, assess model reliability and improve regional climate predictions.

Depth-dependent intrinsic and scattering seismic attenuation in north central Italy

SUMMARY In this study the attenuation mechanism of seismic wave energy in north central Italy is estimated using low-magnitude earthquake local data recorded at six stations managed by INGV. Most of the analysed events are located along the Alpine chain in the zone of Iseo and Garda lakes, while a minor part in the Po valley. The zone investigated is characterized by the occurrence of significantly intense earthquakes (magnitude up to 6.6) the most recent occurred in 2004 close to the city of Salo on the coast of the Garda lake (Mw= 5.0). Due to the high population density and presence of industrial activity the investigated area is characterized by a high seismic risk. First, the ordinary Multiple Lapse Time Window Analysis (MLTWA) method is applied in the assumption of uniform velocity and scattering and the couple of B0, the seismic albedo and Le−1, the extinction length inverse (corresponding to the total attenuation coefficient) is calculated in the frequency bands of 1.5, 3, 6 and 12 Hz. To retrieve more realistic estimates, the obtained values of B0 and Le−1 are corrected taking into account the effects of a depth-dependent earth model, consisting of an earth structure characterized by a transparent upper mantle and a heterogeneous crust. We find that the corrected intrinsic and scattering attenuation parameters (which are proportional to the inverse of the intrinsic/scattering quality factors, Q−1I and Q−1S) are strongly frequency dependent, with a prevalence of scattering attenuation over the intrinsic dissipation. The corrected and uncorrected values of total Q are in agreement with the total Q values obtained with different approaches for the same area.

Supply chain scheduling and coordination with dual delivery modes and inventory storage cost

We study a two-echelon supply chain scheduling problem in which a manufacturer acquires supplies from an upstream supplier and processes orders from the downstream retailers. The supply chain sells a single short-life product in a single season. We consider the scenario where the manufacturer can only accept some of the orders from the retailers due to its supplier's common production time window and its own two common production and delivery time windows. The upstream supplier processes materials and delivers the semi-finished products to the manufacturer within its time window. Then the manufacturer further processes these products to produce finished products and delivers them to the retailers within its two time windows, where one window is for production and normal delivery, and the other is for production and express delivery. Having to store the materials before processing them, the supplier incurs a storage cost, which depends on the order size and storage time. The manufacturer pays the transportation cost for delivering the finished products to the retailers. Due to double marginalization, the performance of the supply chain is sub-optimal. We model the supply chain problem as a flow shop scheduling problem with multiple common time windows. We derive some dominance properties and establish some theorems that help solve the sequencing problems for the orders and eliminate the idle time among the orders. Based on these results, we develop fast pseudo-polynomial dynamic algorithms to optimally solve the problem. We prove that the problem is NP-hard in the ordinary sense only. We develop two practically relevant and robust methods for the supply chain to achieve optimal profit-making performance through channel coordination.

Batch machine production with perishability time windows and limited batch size

This article provides a theoretical analysis of the problem of scheduling jobs in batches by family on a batch-processing machine, in the presence of perishability time windows of equal length. The problem arises in the context of production planning in a microbiological laboratory, and has application in wafer-fab production and for wireless broadcasting. The combined features of multiple families and time windows are new to the literature. The study is restricted to unit job processing times. We prove that the problem is NP-hard, thus solving an open problem by Uzsoy [24]. A Dynamic Programme is developed, with running time polynomial in the input variables of maximum batch size, the number of families and the length of the demand time horizon. In addition, we show that an heuristic approach to minimising the perishability time window can provide a 2-approximation to the optimum.

Truck Driver Scheduling in the United States

The U.S. truck driver scheduling problem (US-TDSP) is the problem of visiting a sequence of λ locations within given time windows in such a way that driving and working activities of truck drivers comply with U.S. hours-of-service regulations. In the case of single time windows it is known that the US-TDSP can be solved in O(λ3) time. In this paper, we present a scheduling method for the US-TDSP that solves the single time window problem in O(λ2) time. We show that in the case of multiple time windows the same complexity can be achieved if the gap between subsequent time windows is at least 10 hours. This situation occurs, for example, if, because of opening hours of docks, handling operations can only be performed between 8.00 a.m. and 10.00 p.m. Furthermore, we empirically show that for a wide range of other problem instances the computational effort is not much higher if multiple time windows are considered.

Attenuation Characteristics of Taiwan: Estimation of Coda Q, S-wave Q, Scattering Q, Intrinsic Q, and Scattering Coefficient

Research Article| September 01, 2010 Attenuation Characteristics of Taiwan: Estimation of Coda Q, S-wave Q, Scattering Q, Intrinsic Q, and Scattering Coefficient Fangyin Zhang; Fangyin Zhang 1Weidlinger Associates Inc., 375 Hudson Street, New York, NY 10014, USA Search for other works by this author on: GSW Google Scholar Apostolos S. Papageorgiou Apostolos S. Papageorgiou 2Department of Civil Engineering, University of Patras, Patras, Greece Search for other works by this author on: GSW Google Scholar Seismological Research Letters (2010) 81 (5): 769–777. https://doi.org/10.1785/gssrl.81.5.769 Article history first online: 09 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Fangyin Zhang, Apostolos S. Papageorgiou; Attenuation Characteristics of Taiwan: Estimation of Coda Q, S-wave Q, Scattering Q, Intrinsic Q, and Scattering Coefficient. Seismological Research Letters 2010;; 81 (5): 769–777. doi: https://doi.org/10.1785/gssrl.81.5.769 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietySeismological Research Letters Search Advanced Search A dataset of 5,499 seismograms recorded at 71 short-period stations (distributed over the island of Taiwan) and generated by 108 earthquake events that occurred over a period of time from 2000 to 2003, with a magnitude ranging from ML = 3.0 to 5.0 and depths from 2.0 km to 31.0 km, were used to estimate attenuation characteristics of the lithosphere of Taiwan. The results of the analyses provide evidence that: 1) The S-wave attenuation \(Q_{{\beta}}^{-1}\) (as estimated from the coda normalization method) is in very good agreement with total attenuation \(^{T}Q_{S}^{-1}\) (as estimated from multiple lapse time window... You do not have access to this content, please speak to your institutional administrator if you feel you should have access.

Kīholo Bay, Hawai‘i, earthquake sequence of 2006: Relationship of the main shock slip with locations and source parameters of aftershocks

We study the source process of the Kīholo Bay earthquake (MW 6.7), which occurred beneath the northwest part of the Island of Hawai‘i on 15 October 2006, and static stress drops of small earthquakes that occurred in 2006 and 2007 around the main shock including aftershocks. We relocate the aftershocks to determine the fault plane from the two nodal planes. The relocated aftershocks define an E‐W trending plane that dips to the south, in good agreement with one of the nodal planes given by the Global Centroid Moment Tensor solution. Waveform inversion is performed with multiple time windows to investigate the rupture speed and the slip distribution of the main shock. Waveforms of an aftershock with MW 5.2 are used to calculate empirical Green's functions. Our results indicate that the rupture propagated unilaterally to the west with a rupture speed greater than 3.0 km/s (63% of the shear wave velocity). This westward rupture is consistent with the fact that aftershocks are distributed predominantly to the west of the main shock epicenter. Most aftershocks are located on the edge of patches with a large slip, or asperities and some also occur inside the patches. We also estimate static stress drops of 39 earthquakes (2.5 &lt; ML &lt; 3.5) that occurred in 2006 and 2007 near the source region of the Kīholo Bay earthquake. Static stress drops range from 0.12 to 8.6 MPa and aftershocks around large slip patches of the main shock likely to have larger stress drops.

Study of attenuation mechanism for Garwhal–Kumaun Himalayas from analysis of coda of local earthquakes

The relative contribution of intrinsic ( Q i − 1 ) and scattering ( Q s − 1 ) attenuation to seismic wave attenuation was estimated for the Garwhal–Kumaun Himalayas using Multiple Lapse Time Window Analysis (MLTWA) method under the assumption of isotropic scattering. Local earthquake data recorded by an array operated by Wadia Institute of Himalayan Geology (WIHG), India was used for this purpose. It is observed that scattering attenuation primarily contributes to seismic wave attenuation in this region and its value is much higher compared to that of intrinsic attenuation at around 1 Hz frequency. As frequency increases the relative contribution of scattering attenuation to total attenuation starts decreasing. However, as seismic albedo is higher than 0.5 for all the frequencies considered, it is concluded that the medium here is highly heterogeneous in nature.

Depth dependent seismic scattering attenuation in the Nuevo Cuyo region (southern central Andes)

In the present work we separated intrinsic from scattering attenuation coefficients both for the crust and the upper mantle in the tectonically highly active areas of the Southern‐Central Andes ‐ Nuevo Cuyo region, analyzing two groups of earthquakes, well separated in depth. This region is characterized by the presence of flat subduction. We apply MLTWA (Multiple Lapse Time Window Analysis), coda normalization and Q‐coda techniques to measure the scattering and intrinsic attenuation coefficient and the total Q for S waves. We find that intrinsic attenuation does not decrease with depth whereas scattering attenuation is higher in the crust than in the upper mantle, and that intrinsic attenuation predominates over scattering attenuation. We interpret this observation in terms of the release of water and other fluids into the overlying lithosphere due to the dynamics of the subduction process, in agreement with most of the prevalent geodynamic models.

A New Model for Estimating Real-time Travel Time on a Signalized Arterial

A new model for estimating the real-time travel time on a signalized arterial is developed in this paper.The basic idea behind the proposed model is that the time horizon analyzed is first divided into multiple time windows,and these time windows are then further divided into shorter time intervals.In the paper,the arterial system states are defined as whether the vehicles at the stopping line of an intersection queue or not.After the determination of the arterial system states at each time interval within each time window,a stochastic process with memoryless property is then established. Consequently,the travel time on a signalized arterial within a time window can be estimated by using the discrete-time Markovian decision process(DTMDP).This process is applied repeatedly to each time window,and the real-time travel time on the signalized arterial over the time horizon is then obtained.Compared to the previous related models,the model's inputs only include the data of traffic flow and signal setting,the proposed model's parameters are less and easier to calibrate,the cost of model application is low,and the model has a good transplant property as well.Finally,the model proposed in this paper is validated on an actual signalized arterial in Guangzhou.

Spatial distribution of scattering loss and intrinsic absorption of short-periodSwaves in the lithosphere of Japan on the basis of the Multiple Lapse Time Window Analysis of Hi-net data

SUMMARY Propagation of short period S waves through the crust is strongly controlled by scattering loss and intrinsic absorption. Scattering loss controls the shape of the seismic envelope and the spatial distribution of the energy while intrinsic absorption produces an exponential decay as a function of time which is independent of the coordinates. Since both parameters have a different effect, it is possible to compute them by means of the Multiple Lapse Time Window Analysis (MLTWA). In this paper, high resolution maps of Japan for both seismic S-wave attenuation parameters are obtained by using the MLTWA with data provided by the Hi-net seismic network. The maps show strong regional variation of the parameters. The variations depend mainly on the tectonic setting of each region and volcanism mechanisms. In the scattering loss maps, in the 1–2 Hz map, there is a very different behaviour between the northeast (stronger scattering loss) and the southwest (much weaker scattering loss). In the northeast of Japan, areas with strong scattering loss correspond mainly to the location of the volcanic arcs. In Southwest Japan, Chugoku region and the west side of Kii peninsula show strong scattering levels for the 4–8 Hz and higher frequency bands. In Hokkaido, strong scattering loss and intrinsic absorption can be observed for the lower frequency bands. In the Sendai plain, we find strong scattering loss for all the frequency bands. Under all these areas low velocity anomalies have been detected in previous works. In Tohoku area the east side shows lower intrinsic attenuation than the west side. This characteristic seems to extend to the southern part of Hokkaido and to central Japan. In Kanto area, the values of intrinsic absorption are lower than in the surrounding areas; but in the region around the Itoigawa-Shizuoka tectonic line and in its western side strong absorption areas are observed. The behaviour of each area for intrinsic absorption is similar to the behaviour observed in the Q−1c maps. The MLTWA is based on the hypothesis of multiple isotropic scattering in a medium with the homogeneous distribution of scattering mean free path and intrinsic absorption. Although these hypotheses are very simple, the results are very informative on the characteristics of each region, and show the usefulness of studying the properties of scattered seismic waves in the understanding of the properties of the crust.

Frequency-dependent attenuation of S-waves in the Kanto region, Japan

AbstractApparent, scattering, and intrinsicS-wave attenuations (QS−1,Qscat−1andQint−1) of the upper lithosphere in the Kanto region of Japan were measured in the 1- to 32-Hz frequency range using Multiple Lapse Time Window Analysis (MLTWA) for 115 borehole seismograms of local earthquakes. A new set of time windows for MLTWA, in which multiple isotropic scattering is assumed, was proposed and employed to estimate the frequency dependence ofS-wave attenuation parameters. Scattering attenuation was found to dominate intrinsic attenuation in theS-wave attenuation mechanism at low frequencies (&lt;;2 Hz), whereas the opposite relation was observed at high frequencies. The transition is caused by the different frequency dependences ofQscat−1(∝f−1.5) andQint−1(∝f−0.7) at this frequency. Interestingly,Qscat−1is almost frequency independent at frequencies &gt;8 Hz, which implies the self-similar nature of short-wavelength heterogeneities in the upper lithosphere. In terms of the upper lithosphere of the Kanto region, these results may indicate that the random heterogeneities characterized by the Gaussian autocorrelation function with a fractional fluctuationε≈ 10% and a correlation lengtha≈ 2 km are superimposed on the weak background self-similar heterogeneity.

Heuristics for the multi-period orienteering problem with multiple time windows

We present the multi-period orienteering problem with multiple time windows (MuPOPTW), a new routing problem combining objective and constraints of the orienteering problem (OP) and team orienteering problem (TOP), constraints from standard vehicle routing problems, and original constraints from a real-world application. The problem itself comes from a real industrial case. Specific route duration constraints result in a route feasibility subproblem. We propose an exact algorithm for this subproblem, and we embed it in a variable neighborhood search method to solve the whole routing problem. We then provide experimental results for this method. We compare them to a commercial solver. We also adapt our method to standard benchmark OP and TOP instances, and provide comparative tables with state-of-the-art algorithms.