Multiple Trips Research Articles

Charles W. Bergquist (1942–2020)

Charles W. Bergquist (1942–2020)

Analysis of Overweight Truck Permit Policy in New Jersey

The roadway infrastructure constantly deteriorates because of environmental conditions, but other factors such as exposure to heavy trucks exacerbates the rate of deterioration. Therefore, decision-makers are constantly searching for ways to optimize allocation of the limited funds for repair, maintenance, and rehabilitation of New Jersey’s infrastructure. New Jersey legislation requires operators of overweight (OW) trucks to obtain a permit to use the infrastructure. The New Jersey Department of Transportation (NJDOT) issues a variety of permits based on the types of goods carried. These permits allow OW trucks to use the infrastructure either for a single trip or for multiple trips. Therefore, one major concern is whether the permit revenue of the agency can recoup the actual cost of damage to the infrastructure caused by these OW trucks. This study investigates whether NJDOT’s current permit fee program can collect enough revenue to meet the actual cost of damage to the infrastructure caused by these heavy-weight permit trucks. The infrastructure damage is estimated by using pavement and bridge deterioration models and New Jersey permit data from 2013 to 2018 containing vehicle configuration and vehicle route. The analysis indicates that although the cost of infrastructure damage can be recovered for certain permit types, there is room for improvement in the permit program. Moreover, based on permit rules in other states, the overall rank of the New Jersey permit program is evaluated and possible revisions are recommended for future permit policies.

QS5: Cryopreserved Adipose for Hypodermal Augmentation After Full-thickness Burns

Purpose:Burn and blast injuries to the face and extremities are highly morbid injuries affecting quality of life, ability to work, and psychosocial well-being. Without exception, extensive burn injuries require surgical debridement, with standard of care reconstruction involving autologous skin grafting to restore cutaneous integrity. This treatment modality is limited in extensive burns or in highly visible areas by lack of donor site and/or soft tissue deficits resulting in significant disfigurement. Hypodermal restoration via autologous adipose transplantation provides padding for the overlying skin, helps restore native features, and enhances contour and texture. However, this technique is limited by graft retention and often requires multiple rounds of grafting and consequently, multiple rounds of surgery, each with separate anesthesia, to achieve adequate results. The goal of this study was to demonstrate the therapeutic validity and efficacy of utilizing cryopreserved adipose to avoid multiple liposuction events when serial skin and fat grafting procedures are performed to restore epidermal, dermal, and hypodermal integrity after full-thickness burn.Methods:Adipose was collected from female Yorkshire swine and processed day-of-collection for immediate cryopreservation. This adipose was preserved for 3 months prior to initiation of the next stage of the experiment. After three-month elapse, female Yorkshire swine received 16, 4x4 cm full-thickness burns using an electric brand. After 48 hours, eschar was removed down to fascia. Skin grafts were collected as split-thickness skin grafts. The pigs were maintained for 8 weeks from time of engraftment and interval serum, photography, ultrasound, and biopsies were collected. At 8 weeks post-engraftment animals were sacrificed and all wounds were collected for histology and proteomic evaluation.Results:Split thickness skin graft take was greater than 95% in all injuries. Adipose grafts from Group B, were noted to remain present and incorporated into the granulation tissue in absence of skin graft with viability confirmed on biopsy. Initial increase in granulation layer thickness was noted in presence of fat graft with Group B vs. Group A. On serial ultrasound assessment, penetrating adipose grafts from Group D were noted to be present without gross resorption at all time points. Cryopreserved adipose remained viable throughout the duration of the experiment with histologic evidence of incorporation at 8 weeks post-operative.Conclusion:Burn and blast injuries predominantly affect military personnel and first responders for whom improvement in protective equipment has decreased mortality without resolving the risk of morbidity to the face or extremities. Hypodermal augmentation with lipografting as part of a strategy of autologous skin grafting addresses contour deficits and skin quality, however is limited by the need for multiple liposuction and grafting procedures, requiring multiple trips to the operating room with increased surgical and anesthetic risk and high economic burden. Here we demonstrate cryopreservation of adipose as an avenue to alleviate that burn.

Multi-Objective Energy Management and Charging Strategy for Electric Bus Fleets in Cities Using Various ECO Strategies

The paper presents use case simulations of fleets of electric buses in two cities in Europe, one with a warm Mediterranean climate and the other with a Northern European (cool temperate) climate, to compare the different climatic effects of the thermal management strategy and charging management strategy. Two bus routes are selected in each city, and the effects of their speed, elevation, and passenger profiles on the energy and thermal management strategy of vehicles are evaluated. A multi-objective optimization technique, the improved Simple Optimization technique, and a “brute-force” Monte Carlo technique were employed to determine the optimal number of chargers and charging power to minimize the total cost of operation of the fleet and the impact on the grid, while ensuring that all the buses in the fleet are able to realize their trips throughout the day and keeping the battery SoC within the constraints designated by the manufacturer. A mix of four different types of buses with different battery capacities and electric motor specifications constitute the bus fleet, and the effects that they have on charging priority are evaluated. Finally, different energy management strategies, including economy (ECO) features, such as ECO-comfort, ECO-driving, and ECO-charging, and their effects on the overall optimization are investigated. The single bus results indicate that 12 m buses have a significant battery capacity, allowing for multiple trips within their designated routes, while 18 m buses only have the battery capacity to allow for one or two trips. The fleet results for Barcelona city indicate an energy requirement of 4.42 GWh per year for a fleet of 36 buses, while for Gothenburg, the energy requirement is 5 GWh per year for a fleet of 20 buses. The higher energy requirement in Gothenburg can be attributed to the higher average velocities of the bus routes in Gothenburg, compared to those of the bus routes in Barcelona city. However, applying ECO-features can reduce the energy consumption by 15% in Barcelona city and by 40% in Gothenburg. The significant reduction in Gothenburg is due to the more effective application of the ECO-driving and ECO-charging strategies. The application of ECO-charging also reduces the average grid load by more than 10%, while shifting the charging towards non-peak hours. Finally, the optimization process results in a reduction of the total fleet energy consumption of up to 30% in Barcelona city, while in Gothenburg, the total cost of ownership of the fleet is reduced by 9%.

STUDI ALGORITMA IGVNS, ALGORITMA GVNS, DAN ALGORITMA ABC PADA MULTIPLE TRIP VEHICLE ROUTING PROBLEM (MTVRP)

The Multiple Trip Vehicle Routing Problem (MTVRP) is one of the VRP variants with vehicle capacity constraints, and the limited number of vehicles allows each vehicle to distribute more than one route so as to minimize the number of vehicles used. The algorithm used in this study is the Improved General Variable Neighborhood Search (IGVNS) algorithm. The IGVNS algorithm is a hybrid between the GVNS algorithm and the VNS algorithm. The calculation results of the IGVNS algorithm will be compared with the GVNS algorithm and the ABC algorithm. The main stages of the IGVNS and GVNS algorithms are initial solution formation, perturbation, and solution improvement. The main stages of the ABC algorithm are initialization, solution improvement and optimization. Based on manual calculations using 8 points, the ABC algorithm produces a distance of 86 km and a service time of 1.47 hours, the GVNS algorithm produces a distance of 80 km and a service time of 1.37 hours, the IGVNS algorithm produces a distance of 79 km and service time is 1.35 hours. Based on one example of the ABC algorithm, the calculation solution using the IGVNS algorithm shows more optimal results. Based on the results of parameter testing, the v max parameter affects the calculation results, that is the greater the v max value, the more optimal the resulting solution. While the a max parameter does not affect the calculation results because it shows constant results in two successive iterations carried out.

Adaptive routing behavior with real-time information under multiple travel objectives

Real-time information about traffic conditions is becoming widely available through various media and connected-vehicle technology. In such conditions, travelers have better knowledge about the system and adapt as the system evolves dynamically during their travel. Drivers may change routes during their travel in order to optimize their own objective of travel. Various travel objectives are captured in mathematical models via disutility functions. The focus of this research was to study the behavior of travelers with multiple trip objectives when they are provided real-time information, and assess their ability to determine “optimal” routing policies, compared to exact solutions based on the online shortest path problem. A web-based experiment was carried out to simulate a traffic network with limited information provision. The decision strategies of participants were analyzed and compared to a variety of decision policies established in the literature – optimal, greedy, and a priori – and a general model to describe the observed travelers’ decision strategies was calibrated from over 40,000 decision points extracted from the collected data. Apart from trip objective, other factors such as relative position in the network and experience gained were found to influence user decisions. This research is a step towards calibrating equilibrium models for adaptive behavior with multiple user classes.

Incentive-driven transition to high ride-sharing adoption

Ride-sharing—the combination of multiple trips into one—may substantially contribute towards sustainable urban mobility. It is most efficient at high demand locations with many similar trip requests. However, here we reveal that people’s willingness to share rides does not follow this trend. Modeling the fundamental incentives underlying individual ride-sharing decisions, we find two opposing adoption regimes, one with constant and another one with decreasing adoption as demand increases. In the high demand limit, the transition between these regimes becomes discontinuous, switching abruptly from low to high ride-sharing adoption. Analyzing over 360 million ride requests in New York City and Chicago illustrates that both regimes coexist across the cities, consistent with our model predictions. These results suggest that even a moderate increase in the financial incentives may have a disproportionately large effect on the ride-sharing adoption of individual user groups.

On the optimization of the bus network design: An analytical approach based on the three-dimensional macroscopic fundamental diagram

Multiple factors can influence the public transport level of service. All take root in the network structure and the operating regime, i.e. how the bus lines are arranged atop the street network and how the service frequency is adjusted to meet urban mobility patterns. This is known as the bus network design problem and has been the subject of several studies. The problem is so challenging that most studies until now resort to strong assumptions such as a static description of the peak hour demand, homogeneous user behavior, and equal trip lengths. Potential effects of different types of user behavior and trip lengths patterns on the user and/or operator cost have not been investigated whatsoever. Moreover, none of the existing studies have considered the effects of bus network structure on private car users, the level of interactions between the modes, and the passenger mode choice that depends on traffic conditions.This paper aims to close this gap and provide a general framework considering multiple trip length patterns, two types of user behavior, and the effects that the bus network structure might have on the traffic performance and passenger mode choice. For modeling different trip length patterns, we use the trip length distribution as an intermediate level of abstraction. To capture complex modal interactions and quantify the operating speeds, we apply the recently proposed three-dimensional macroscopic fundamental diagram. We use the operating speed for each mode to determine the mode choice at the trip length level. This way, we are able to solve the optimal bus network design problem under the free-flow/saturated traffic conditions in an analytical way, while considering more realistic settings including a dynamic description of the peak hour demand, mixed traffic, and different mode choice decisions depending on trip lengths and walking preferences.Numerical analysis reveals that all the tested factors, including demand intensity, user behavior, and trip length patterns, have significant effects on the operator and user cost function. Results show that the probability of choosing any given mode follows certain distribution that varies across the trip length patterns, indicating the importance of modeling the mode choice at the trip length level. Furthermore, the results indicate that users can benefit if they are willing to adjust the number of transfers to minimize the walking distance at the origin and the destination. Moreover, we show that the optimal bus network design determined for the uniform trip pattern underestimates the number of required buses, which leads to passenger congestion at stops during the peak period. This, however, does not happen when we take into account the actual trip length distribution for the bus network design. A comparison with a simplified approach that considers the bus system only, reveals the value of accounting for the complex bi-modal interactions, especially for higher demand levels. Finally, we show that by allowing the design parameters to vary across cardinal directions we provide more flexibility for the bus system to serve the passenger demand while reducing the operator cost compared to the existing approaches.

ZAC: A Zone Path Construction Approach for Effective Real-Time Ridesharing

Real-time ridesharing systems such as UberPool, Lyft Line, GrabShare have become hugely popular as they reduce the costs for customers, improve per trip revenue for drivers and reduce traffic on the roads by grouping customers with similar itineraries. The key challenge in these systems is to group the right requests to travel in available vehicles in real-time, so that the objective (e.g., requests served, revenue or delay) is optimized. The most relevant existing work has focussed on generating as many relevant feasible (with respect to available delay for customers) combinations of requests (referred to as trips) as possible in real-time. Since the number of trips increases exponentially with the increase in vehicle capacity and number of requests, unfortunately, such an approach has to employ ad hoc heuristics to identify relevant trips.To that end, we propose an approach that generates many zone (abstraction of individual locations) paths – where each zone path can represent multiple trips (combinations of requests) – and assigns available vehicles to these zone paths to optimize the objective. The key advantage of our approach is that these zone paths are generated using a combination of offline and online methods, consequently allowing for the generation of many more relevant combinations in real-time than competing approaches. We demonstrate that our approach outperforms (with respect to both objective and runtime) the current best approach for ridesharing on both real world and synthetic datasets.

Barriers to and facilitators of uptake and sustained use of LPG through the PMUY in tribal communities of Pune district

The Pradhan Mantri Ujjwala Yojana (PMUY), launched in India in 2016, is the world's largest program to provide cleaner cooking fuel to poor households. The PMUY may yield large health benefits because of increased LPG use, and more importantly, reduced chulha use, and thus may significantly reduce household air pollution exposures. This research, conducted in a tribal, difficult-to-reach area of Pune District, leveraged PMUY to study the uptake, adoption, usage, and health benefits of LPG. This work highlighted barriers to and facilitators of adoption and sustained LPG usage. Our findings have program implications and need to be addressed to ensure that poor households continue to use LPG as their primary cooking fuel.Our study indicates that most households expressed a desire to own an LPG gas stove but are not aware about the methods to avail the scheme and rely on the local governments to obtain the LPG. The perceived benefits of using LPG differ among people, depending on their own experiences. The most common perceived benefits include ease of use and less time spent on cooking. However, most people are unaware of the severe health effects of HAP, which, if known, might influence their decision to own and use LPG for cooking. The challenges in availing the scheme include varying registration amount, lesser awareness of the document requirements and multiple trips to the distributors' office to fulfil the documentary requirements. Further, the sustained use is hampered by the non-subsidized refills and unavailability of transport facilities for the refill replacement. Further, the beneficiaries are unaware that the subsidy goes towards the repayment of the loan and more clarity is expected from the distributor when availing the scheme.In conclusion, the population in tribal regions is willing to use the LPG regularly if the refill costs are subsidized. Further increasing logistical and financial support to rural distributors will help in better uptake.

The Effectiveness of Clarke Wright and Sequential Insertion Algorithm in Distribution Routing Aqua

With the Multiple Trips condition, the results obtained for the optimal distance route that starts and stops at PT. Tirta Investama Medan with Clarke Wright Algorithm at t = 1 is 22 km and at t = t + 1 is 15.2 km. While the optimal travel distance route with the Sequential Insertion Algorithm at t = 1 is 15.05 km, and at t = t + 1 is 22.9 km. Clarke Wright Algorithm looks for an optimal solution to get the best route, while Sequential Insertion Algorithm has an excess in the election of a customer by considering customer position with available insertion track location until all customer have been assigned. The Clarke Wright Algorithm obtained a total distance of 37.2 km. In comparison, the Sequential Insertion Algorithm solution obtained a total distance of 37.95 km. It can be concluded that the route formed using the Clarke Wright Algorithm in this case is more effective than using the Sequential Insertion Algorithm.

The benefits of multiple arts-based field trips

The near-term social-emotional and academic benefits of arts-based field trips has been well documented, but a new study shows that multiple arts-based field trips can have positive effects that endure for multiple years. Laura Florick, Jay P. Greene, Rebecca Levenberg, and Rebecca Pogue describe a partnership between a school district and arts center in Atlanta in which students go on three field trips during the school year. Researchers sorted students into groups, with some attending all three field trips and others attending only one. Student surveys and school data provide evidence of the benefits of going on multiple field trips.

Migrant Conversions: Transforming Connections between Peru and South Korea

Erica Vogel’s monograph, which highlights the multifaceted and complicated lives of migrants from the global South in their pursuit of a place in the economy of the global North, is an in-depth ethnographic work spanning five years (2006–11) across Asia and Latin America. While this volume is a welcome addition to the literature focused on the lives of migrants in the field of World Christianity, it also extends itself into accounting for the economic and social dimensions of their experience.Vogel specifically hones in on the lives of Peruvian migrants in South Korea, and in many cases their return to Peru, whether voluntary or involuntary. Her work involved multiple months and trips spanning back and forth between South Korea and Peru. This element of a dual site of research gives the study a balance in following the migrants after their return to their place of origin.The book masterfully paints portraits of the Peruvian migrants wedged in the flux of global economies and showcases their desire to participate in this cosmopolitan arena. Their conversion exemplifies this constant shifting of identities and economic realities, whether, in some cases, a renewed Christian faith, or others, such as their many attempts to send remittances to their family in Peru while balancing their precarious status in a South Korea caught between economic growth and simultaneous decline. Vogel uses the concept of “conversion” as the central heuristic to read the migrants’ lives and their interactions. Conversion is used and developed in three main ways: economic, spiritual, and cosmopolitan. The migrants seen through this lens are always in a state of conversion thus becoming something new, whether in trying to “convert” their hard-earned South Korean Won into “Migradollars” or quite literally trying to “convert” their fellow migrants to their newfound faith in a foreign land.The book is composed of four sections, which follow this sequence of conversions throughout the book. The first chapter serves as a general introduction and outline of the ethnography, offering critical insights into the global picture of economics and migratory policy. It recounts how the research came about and how it developed transnationally, from South Korea to Peru and back. The second chapter kicks off this search for finding “conversion” in a comprehensive study on the dynamics of remittances and their social power in their homeland. This chapter’s strength is that it offers a detailed and insightful look at the double-edged nature of remittances, in some cases propelling families out of poverty while in others plunging them deeper into poverty. The third chapter follows the migrants’ lives in various faith congregations in South Korea, one Catholic, and two Protestant. This section details the religious landscape of a South Korea in the places where migrants convert, worship, and socialize in the undocumented margins of the country. It centers on how this dimension of their migrant experiences becomes, in many cases, the pivotal part of their self-understanding and purpose in migrating to South Korea. The final chapter looks at the Peruvian migrants’ attempts to participate in cosmopolitan projects through marriage to foreigners, education, and new opportunities. The epilogue offers some concluding remarks and some closure to the various characters’ lives who had been interviewed in the book.The author’s notion of conversion is critical to her understanding of migrants’ lives and their desire to convert their labor into remittances that will help their families and set them up as citizens of a global economy regardless of the precarious nature of their status as undocumented workers. On the other hand, however, it shows how, for many, “conversion” to a new faith and, in some cases, “renewal” from a nominal faith into a fervent faith repositions these migrants not merely as undocumented migrants but also as “missionaries,” evangelists, and pastors in their foreign home. Thus, this is a compelling way to look at the migrants’ experience through these lenses, but like many concepts, they are not flawless and risk becoming overdetermined.The monograph is eloquently written and highlights the conversations between the researcher and the interviewees. In a work complete with graphs showing economic fluctuations, color photos, and timelines, Vogel presents her material pedagogically and with a keen eye for clarity. Though the length of this text is relatively short (188 pp.), it leaves the reader with a desire to delve deeper into the migrants’ testimonies and rationales. Its brevity is therefore a plus, making it accessible and easy to engage, thus providing a text that would be ideal for an audience interested in transnationalism, global economics, and the spiritual dimension of migration.

Harvesting and evacuation route optimisation model for fresh fruit bunch in the oil palm plantation site

As one of the major vegetable oils, the sustainability development in the palm oil industry is a critical concern among the global community. Majority of the sustainability concerns relate to the plantation practises which were claimed to be inefficient and create pollution. This paper explores the issues associated with the oil palm plantation site, specifically in the fresh fruit bunch (FFB) harvesting and evacuation process that known to be a labour and energy intensive process. A novel mathematical model was proposed to determine the shortest distance required to collect harvestable FFBs within the site. The model was demonstrated on various scenarios within the oil palm plantation site, including the differences in floorplan shape, distribution of harvestable trees, and loading capacity of transporter. The results have shown that the proposed model is capable to propose the shortest route(s) for different plantation site to reduce the travelled distance. Vertical rectangular plantation layout was found to have the highest reduction in travelled distance at 21% as compared to other floorplans; and the impact of the reduction in travelled distance is most noticeable at low harvestable tree distribution (60%) at 26.4%. Lastly, the proposed model was demonstrated to be able to propose a multiple trips solution when a low loading capacity transporter (wheelbarrow), which is a critical solution for small and medium enterprise farmers.

Spatial Planning Framework for Development of Rural Activity Centers: Method of Location Allocation, Effect on Trip Length, and Policy Implications

Activity center (AC) location allocation is a central concept for better quality of life, poverty reduction, accessibility maximization, and minimization of trip length and cost. An AC is characterized by p number of basic facilities present within it. The proposed framework identifies heuristically the potential locations of ACs that consist of multiple basic facilities. This article proposes a spatial planning framework to help policymakers while making infrastructure development decisions within budgetary limitations. For the application of this planning framework, a rural district in India is considered to allocate the location of ACs with four facilities: a health-care center, high school, bank, and market. The effect of AC developments on trip length is analyzed by preparing different activity chains to complete multiple trip purposes. Two cases are considered for location allocation of ACs. In the first case, we assumed that there is no facility existing in the study area; the latter case dealt with a situation where there are facilities already existing. In the case analysis, four categories of ACs are configured: AC4 with all four facility types, AC3 with any three facility types, AC2 with any two facility types, and AC1 with a single facility. Findings revealed that considerable trip cost savings in terms of trip length reduction could be realized from AC4 type activity centers over all other categories of AC. The policy context discussed in this article will not only help in maintaining uniformity in socioeconomic services over the region, but also, balance population density in physically isolated areas and densely populated areas. With the illustrated application, all the identified ACs with partial services within a region can be augmented to become full-fledged ACs in a phased manner, where infrastructure financing is constrained, particularly in lower and middle-income economies. In summary, the research framework will improve the quality of life in rural regions with a focus on better health, improved education, and an enhanced economy.

Slime mould algorithm constrained by the relay operating time for optimal coordination of directional overcurrent relays using multiple standardized tripping curves

In this paper, a new stochastic optimizer called slime mould algorithm (SMA) for solving the optimal coordination of directional overcurrent relays in meshed power networks is proposed. The proposed SMA-based method deals with the coordination problem using the most recent digital relays by selecting the optimal tripping standardized curve plus time dial and current pickup. Afterwards, the problem gets more sophisticated by bounding the relay tripping time inside a practical range to simulate the real network conditions. SMA’s performance is evaluated on two different test cases including highly penetrated distributed generators in the second one. The results of SMA are compared with other recent metaheuristic and conventional approaches reported in the literature under same conditions aimed at fair comparisons. It is declared that the SMA attains 29.9% reduction in the relays total operating time for the first test case compared to the well-matured water cycle algorithm. Even, if the tested network is a highly penetrated by distributed generators, more reduction is achieved by 33.7% with better convergence characteristics. It can be established that the SMA-based method demonstrates a competitive and reliable tool for minimizing the relays total operating time satisfying all the constraints even for the sophisticated scenarios.

Mass migration of earthworms in Mawlyngot area, East Khasi Hills, Meghalaya

This paper documents the mass migration of the earthworm, Perionyx macintoshi that occurs annually in Mawlyngot area in Meghalaya, North-East India. Multiple field trips were conducted to this place for four years from 2011-2015 to study this phenomenon. Following field observations, the authors have made an attempt to explain the when’, the ‘why’ and the ‘how’ of this migration.

Reducing time to treatment and patient costs with breast cancer: the impact of patient visits.

The purpose of this study was to evaluate the impact of processes aimed at reducing time to treatment initiation (TTI) on minimizing the days spent to complete pretreatment visits and the associated costs for patients with nonmetastatic breast cancer. System-wide initiatives were implemented in 2014 to minimize TTI, by incorporating multiple strategies (eg, creation of teams, patient liaisons, process mapping) and enhanced communication to increase coordinated visits. Average number of days spent to complete visits, TTI, and associated patient costs including driving expenses, parking, food, childcare, and lost wages were calculated and compared between the years 2015 and 2018. In 2015, the median TTI was 43.5days and the average number of separate days spent to attend multidisciplinary visits prior to first treatment was 1.86. These were reduced to 29days and 1.52 visits, respectively, in 2018 (p<0.0001 for both). When evaluating treatment visits by surgical procedure, the average number of visits was reduced regardless of surgical procedure. The average number of visits was highest for patients undergoing mastectomy with reconstruction (2.34 in 2015, reduced to 1.65 in 2018, p<0.0001). A single visit to complete treatment planning was associated with patient costs of $249 as compared with multiple trips costing $491 for 2 visits and up to $1,226 for 5 visits. In breast cancer patients, implementing processes to reduce time to treatment was associated with fewer visits required prior to treatment initiation, resulting in lower patient costs.

Simultaneous Pickup and Delivery Traveling Salesman Problem considering the Express Lockers Using Attention Route Planning Network.

This paper presents a simultaneous pickup and delivery route designing model, which considers the use of express lockers. Unlike the traditional traveling salesman problem (TSP), this model analyzes the scenario that a courier serves a neighborhood with multiple trips. Considering the locker and vehicle capacity, the total cost is constituted of back order, lost sale, and traveling time. We aim to minimize the total cost when satisfying all requests. A modified deep Q-learning network is designed to get the optimal results from our model, leveraging masked multi-head attention to select the courier paths. Our algorithm outperforms other stochastic optimization methods with better optimal solutions and O(n) computational time in evaluation processes. The experiment has shown that reinforcement learning is a better choice than traditional stochastic optimization methods, consuming less power and time during evaluation processes, which indicates that this approach fits better for large-scale data and broad deployment.

The Multi-Depot Cumulative Vehicle Routing Problem With Mandatory Visit Times and Minimum Delayed Latency

This paper introduces a novel variant of the cumulative vehicle routing problem (CCVRP) that deals with home health care (HHC) logistics. It includes multiple nonfixed depots and emergency trips from patients to the closest depot. The aim is to minimize the system’s delayed latency by satisfying mandatory visit times. Delayed latency corresponds to caregivers’ total overtime hours worked while visiting patients. A new mixed-integer linear programming model is proposed to address this problem. Computational experiments, with more than 165 new benchmark instances, are carried out using the CPLEX and Gurobi MIP solvers. The results indicate that patients’ geographical distribution directly impacts the complexity of the problem. An analysis of the model parameters proves that instances with more depots/vehicles or longer workdays are significantly easier to solve than are original cases. The results show that Gurobi outperforms CPLEX in 55% of the instances analyzed, while CPLEX performs better in only 16% of them. To the best of our knowledge, this is the first VRP that minimizes delayed latency and the first HHC routing study to use a cumulative objective function.