Search

Over the past decade, electric vehicles (EVs) have been considered in a growing number of models and methods for vehicle routing problems (VRPs). This study presents a comprehensive survey of EV routing problems and their many variants. We only consider the problems in which each vehicle may visit multiple vertices and be recharged during the trip. The related literature can be roughly divided into nine classes: Electric traveling salesman problem, green VRP, electric VRP, mixed electric VRP, electric location routing problem, hybrid electric VRP, electric dial-a-ride problem, electric two-echelon VRP, and electric pickup and delivery problem. For each of these nine classes, we focus on reviewing the settings of problem variants and the algorithms used to obtain their solutions.

This paper is focused on solving an industrially-motivated, rich routing variant of the so-called full truckload pickup and delivery problem. It addresses a setting where the distributor has to transport full truckload shipments between distribution centers and customer locations, yet the distributor’s owned fleet is inadequate to perform the totality of the required deliveries and thus a subset of the deliveries has to be outsourced to third-party carriers. In this work, we propose a novel mixed-integer linear programming formulation to model this problem. Using datasets inspired from industrial practice, we evaluate the computational tractability of this model and demonstrate its potential to serve as a decision-support system for real-life operations. Furthermore,we hypothesize that the distributor may realize cost savings when the later portion of the distribution period is utilized to pre-load cargo for delivery during the following period. To that end, we augment the original model to allow for such cargo pre-loading, and we conduct a rolling horizon-based simulation study to quantify its overall economic effect.

Pollution emitted by a vehicle can be checked by reducing the distance traveled and through operational adjustments. Optimized route and simultaneous pickup and delivery in a vehicle routing problem (VRP) can achieve the same. This paper investigates a two-echelon pollution routing problem with simultaneous pickup and delivery by considering multiple time windows (2E-PRPSPD-MTW) for customers’ visit. The first echelon consists of depots and intermediate depots (called satellites), whereas the second echelon consists of the satellites and customers. Two fleets (one for each echelon) of heterogeneous vehicles accomplish pickup and delivery operations. The 2E-PRPSPD-MTW is developed in a bi-objective framework, focusing on minimization of both travel time and fuel consumption. The proposed bi-objective 2E-PRPSPD-MTW is an NP-hard problem. So, in order to optimize it, multi-objective variable neighborhood search (MOVNS) is modified and used. In this process, six operators are proposed in order to improve the neighborhood structure. The suggested operators explore the entire solution space to find the near optimal solution. With the aim of providing much richer insights, the efficacy of the proposed method and mathematical formulation is demonstrated through numerical experiment for a number of instances varying from small to large scale.

A method and system for contactless measurement of the velocity of flight of a thrown body over a measuring base in an air atmosphere and for the actuation of a recording apparatus by the signal formed as a result of the passage of the body through a measuring section are presented. The method proposed is based on the formation of normalized pulses of positive polarity for the synchronization of the activation of a recording apparatus by a definite coordinate of a body thrown. Results of calculation and experimental investigations of variable reluctance pickups in tests of high-velocity ballistic flights are presented. Relations allowing one to estimate the dependence of the magnetic induction in the core of a variable reluctance pickup on the value of the air gap between a magnet and the pickup are presented.

This article addresses the one-commodity pickup and delivery traveling salesman problem (1-PDTSP), which is a generalization of the well-known traveling salesman problem. The 1-PDTSP aims to find a Hamiltonian tour in which a set of supply points (pickup locations), demand points (delivery locations) are visited and, the total traveled distance is minimized. We propose a hybrid metaheuristic based on multi-start evolutionary local search and variable neighborhood descent to solve the 1-PDTSP. To test the performance of our algorithm, we solve instances with up to 500 nodes available in the literature and we demonstrate that our approach is able to provide competitive results when comparing to other existing strategies. Since a direct application of the 1-PDTSP arises as the bicycle repositioning problem, we also use our metaheuristic algorithm to solve a set of real-case instances based on EnCicla, the bicycle sharing system in the Aburra Valley (Antioquia, Colombia).

Efficient feasibility tests are important in many heuristics for routing problems. This paper considers several variants of pickup-and-delivery problems with trailers. Its contribution consists in the description of constant-time procedures for testing observance of capacity constraints when inserting tasks into routes. It is demonstrated that the presence of vehicles with detachable trailers makes capacity feasibility tests considerably more involved.

The online pickup and delivery problem is motivated by the takeaway order delivery on crowdsourcing delivery platform, which is a newly emerged online to offline business model based on sharing economy. Considering the features of crowdsourcing delivery, an online pickup and delivery problem with constrained capacity is proposed, whose objective is to route a delivery man with constrained capacity to serve requests released over time so as to minimize the total latency. We consider online point-to-point requests with single pickup location where each request has to be picked up at the single pickup location and delivered to its destination, and each request become available at its release time, which is not known in advance. The lower bound of this problem for various capacities is proved. Two online algorithms WR and WI are presented, the competitive ratios on a half line and on general metric space are proved respectively. Further, a computational study is conducted to compare the performance of these two online algorithms on random instances of general metric space. The result shows algorithm WR performs better than WI in random cases but not in the worst case.

In dynamic pickup and delivery problems with time windows (PDPTWs), potentially urgent request information is released over time. This gradual data availability means the decision-making process must be continuously repeated. These decisions are therefore likely to deteriorate in quality as new information becomes available. It is still believed that the state of the art for this problem remains far from reaching maturity due to the distinct absence of algorithms and tools for obtaining high-quality solutions within reasonable computational runtimes. This paper proposes a periodic approach to the dynamic PDPTW based on buffering, more specifically a two-step scheduling heuristic which consists of the cheapest insertion followed by a local search. The heuristic’s performance is assessed by comparing its results against those obtained by a mixed integer linear programming model which operates under the assumption that all information is available in advance. Results illustrate how the performance is impacted by urgency levels, the degree of dynamism associated with request arrivals and re-optimization frequency. The findings indicate that increases in dynamism improve solution quality, whereas increases in urgency have the opposite effect. In addition, the proposed approach’s performance is only slightly affected by re-optimization frequency when changing these two characteristics.

This paper studies an extension of the well-known one-to-one pickup-and-delivery problem with time windows. In the latter problem, requests to transport goods from pickup to delivery locations must be fulfilled by a set of vehicles with limited capacity subject to time window constraints. Goods are not interchangeable: what is picked up at one particular location must be delivered to one particular other location. The discussed extension consists in the consideration of a heterogeneous vehicle fleet comprising lorries with detachable trailers. Trailers are advantageous as they increase the overall vehicle capacity. However, some locations may be accessible only by lorries. Therefore, special locations are available where trailers can be parked while lorries visit accessibility-constrained locations. This induces a nontrivial tradeoff between an enlarged vehicle capacity and the necessity of scheduling detours for parking and reattaching trailers. The contribution of the paper is threefold: (i) it studies a practically relevant generalization of the one-to-one pickup-and-delivery problem with time windows. (ii) It develops an exact amortized constant-time procedure for testing the feasibility of an insertion of a transport task into a given route with regard to time windows and lorry and trailer capacities. (iii) It provides a comprehensive set of new benchmark instances on which the runtime of the constant-time test is compared with a naïve one that requires linear time by embedding both tests in an adaptive large neighbourhood search algorithm. Computational experiments show that the constant-time test outperforms its linear-time counterpart by one order of magnitude on average.

Using gas flow to reduce laser plume attenuation is critical in the process control of laser powder bed fusion (LPBF) of metal powders. First, this work investigated Hastelloy X (HX) samples built at different gas flow speeds. Higher porosity with lack of fusion defects was found in the samples built at lower gas flow speeds, which indicates a significant influence of laser plume attenuation. Then, particle pickup experiments were conducted to investigate the limit of further increasing the gas flow speed without disturbing the powder bed. Eight different powders of four alloys (Al, Ti, steel, and Ni) with mean sizes ranging from 25 µm to 118 µm were studied. A model was introduced to predict the pickup speeds of different powders. Lastly, a method based on porosity and particle pickup speed was proposed for the reference of setting the lower and upper limits of gas flow speed in LPBF.

We consider the $$\mathscr {NP}$$-hard twin robot scheduling problem, which was introduced by Erdogan et al. (Naval Res Logist (NRL) 61(2):119–130, 2014). Here, two moving robots positioned at the opposite ends of a rail have to perform automated storage and retrieval jobs at given positions along the gantry rail with a non-crossing constraint. The objective is to minimize the makespan. We extend the original problem by considering pickup and delivery times and present exact and approximation algorithms with a performance ratio of $$\approx \,1.1716$$ for large instances. Further, we compare the presented algorithms in a comprehensive numerical study.

A modified LSM is proposed by introducing an independent micro-rotational inertia, which may help characterize the scale-dependent effect and avoid the Poisson’s ratio limitation of regular triangle lattices in two dimensions. For this method, some factors may affect data pickup and modeling accuracy, but the ‘optimal’ inputs, like stiffness ratio, numerical damping, and micro-rotational inertia, could be obtained from parameter identification by the Dakota toolkit (Adams et al., Tech Rep SAND2010–2183, 2009), when a suitable excitation source function and lattice spacing are set up. By comparing with the modified couple stress theory, we analyze the dispersion relationship of elastic waves for the estimation of the characteristic material length. It shows that this modified LSM may provide an alternative and promising way to investigate the size-dependent wave propagation in elastic media numerically.

To clarify that the performance of an overlap-type sheet separation mechanism is superior to that of the pressure-type and to determine the factor that makes the overlap-type version a multi feed mechanism, we examined the behavior of paper sheets in both mechanisms. First, we introduced models that could calculate the resistance force and feed force acting on the paper sheets in both sheet separation mechanisms. Based on the calculated resistance force and friction force between the paper sheets, we studied the behavior of the paper sheets in each separation mechanism. We found that (1) in the overlap-type sheet separation mechanism, slippage between piled paper sheets theoretically occurs proportionally to the number of the piled paper sheets, and (2) in the pressure-type sheet separation mechanism, slippage between piled paper sheets theoretically occurs only once, regardless of the number of piled paper sheets. Thus, when there are more than three pieces of paper in the separation mechanism, multi feed is more difficult in the overlap-type one, and the overlap-type mechanism is superior to the pressure-type sheet separation mechanism. Furthermore, we found that (3) the overlap-type sheet separation mechanism has a set range for the thickness of paper sheets, which allows it to feed paper sheets one by one, and the performance of multi feed is easily influenced by the feed force caused by the pickup rollers. Finally, (4) the pressure-type sheet separation mechanism is robust with regard to the thickness of the paper sheets and the feed force caused by the pickup rollers.

The use of quasi-zero-stiffness isolators in vibration pickups is investigated in this study. For this purpose, a quasi-zero-stiffness mechanism is first investigated to extract optimal values of parameters guaranteeing these conditions. The frequency response of this type of pickups is then obtained and compared with their equivalent linear pickup to investigate the effects of damping and oscillation amplitude measured by the pickup on the pickup performance. To study the phase distortion, the phase difference between the oscillations exerted on the pickup and those measured by the pickup for various excitation frequencies are measured at quasi-zero-stiffness and their equivalent linear pickups. In this way, the effects of the pickup design parameters on the pickup performance are investigated, and the response of this type of pickups to a sum of two harmonic excitations is studied. Finally, the effects of uncertainties such as friction, noise, etc., on experimental results are investigated.

In this paper, analysis and fabrication of a laboratory model of a five degree of freedom arm robot for pickup and drop applications along with the governing kinematics is investigated. SolidWorks and SimMechanics were applied as the design-fabrication and motion analysis softwares, respectively. To reduce the weight and power consumption and improve the manufacturing time, plexiglas was used as the fabrication material. A novel geometric approach for the inverse kinematics is proposed and as a consequence the addition of the orientation of the specimen along with the location of the end effector as the inputs of the inverse kinematics problem, resulted in the improved workspace and minimum computational error, which enhanced the robot efficiency. The proposed novel inverse kinematics scheme is based on the formulation of the end effector position in terms of the global coordinates and the geometry of the robot; and accordingly determining the join angles in terms of the governing parameters and the desired end effector position. The proposed method led to a considerable reduction of positioning error. In order to validate the simulation outputs, the corresponding results are compared to those of the laboratory model.

In this paper, we develop an intelligent solution to a complex, real-life vehicle routing problem in the waste management sector. Waste management companies deliver various types of empty waste containers to industrial customers, to be filled with different types of waste, after which the containers are picked up again. The full containers are transported to a so-called waste management depot or waste handling depot, where they are emptied, after which they are reused. Empty containers are stocked in various stock depots. Time windows in which containers may be picked up and delivered at the customers and opening hours of the different depots have to be taken into account additionally. Very importantly, there are two types of waste collection trucks that can, respectively, carry one or two containers. The resulting vehicle routing problem belongs to a class of so-called roll-on–roll-off problems, characterized by unit demand. Additionally, the problem discussed in this paper has several characteristics (multiple waste types, multiple container types, multiple depots, a heterogeneous fleet, pickup and delivery, time window constraints, and other) that make solving it a difficult task. To solve this problem, we develop a novel column generation scheme that incorporates a heuristic approach to generate new columns. The master problem is solved by linear relaxation of a set partitioning problem. New routes (columns) are generated by a constructive heuristic loosely based on Solomon’s insertion heuristic for the vehicle routing problem with time windows. The construction heuristic operates on a reformulated version of the roll-on–roll-off problem, i.e., a generalized vehicle routing problem with time windows. The algorithm—called wmpopt—is submitted to an extensive sensitivity analysis to determine its response to different parameter settings. After this, we test it on four real-life problem instances and compare its results to those obtained by a commercial solver. We show that wmpopt achieves much better solutions than the commercial solver in similar computing times.

The current state-of-the-art surgical robotic systems use only a single endoscope to view the surgical field. Research has been conducted to introduce additional cameras to the surgical system, giving rise to new camera angles that cannot be achieved using the endoscope alone. While this additional visualization certainly aids in surgical performance, current systems lack visual-motor compatibility with respect to the additional camera views. We propose a new system that overcomes this limitation. In this paper, we introduce a novel design of an additional “pickup” camera that can be integrated into the da Vinci Surgical System. We also introduce a solution to work comfortably in the various arbitrary views this camera provides by eliminating visual-motor misalignment. This is done by changing the working frame of the surgical instruments to work with respect to the coordinate system at the “pickup” camera instead of the endoscope. Human user trials ( $$N=14$$ ) were conducted to evaluate the effect of visual-motor alignment with respect to the “pickup” camera on surgical performance. An inanimate surgical peg transfer task from the validated Fundamentals of Laparoscopic Surgery (FLS) Training Curriculum was used, and an improvement of 73% in task completion time and 80% in accuracy was observed with the visual-motor alignment over the case without it. Our study shows that there is a requirement to achieve visual-motor alignment when utilizing views from external cameras in current clinical surgical robotics setups. We introduce a complete system that provides additional camera views with visual-motor aligned control. Such a system would be useful in existing surgical procedures and could also impact surgical planning and navigation.

Thermal spray coatings have been widely used on hearth rolls in a continuous annealing line to improve steel sheet quality and prolong the roll service life. One of the common defects formed on a working hearth roll is the oxide pickup. The most common cause of the pickup formation is that the active Mn oxide reacts with coating. The potentials of two different coatings, CoCrAlYTa–Al2O3 (No. 1) and CoCrYNi–Y2O3 (No. 2), to duplicate pickups by reacting with Fe and Mn oxides were studied. There are three stages during pickup producing and growing. No. 2 coating effectively reduced the corrosion of Mn oxide. The characterization and modification of the surface oxide formed can be changed with different dew points. The results indicate that the dew point from − 53 to − 10 °C can change the depth of Mn oxide, such that an alteration can prevent the first stage and second stage and is good for preventing the pickup growing.

Recently, the power system has been changed to introduce the loop power distribution system or the distributed generations for stability and flexibility of power supply. These changes tend to influence on the capacities of protective devices and may cause the malfunctions due to excess of the devices’ capacity. So, as one of the countermeasures of reduction of the fault current, the superconducting fault current limiter (SFCL), has been noticed. However, the reduction of the fault current due to the application of the SFCL in a power distribution system may be able to cause the unexpected malfunctions of the overcurrent relay (OCR). As the OCR, one of the representative protective equipment in a power distribution system, requires the current exceeding the pickup current to be operated, the reduction of the fault current may affect to trip operation of OCR. So, this paper will deal with a trip delay caused by application of the SFCL, which is one of the unexpected malfunctions. To improve OCR’s trip delay, the OCR with voltage component is proposed and the operational characteristics of the OCR with voltage component have been analyzed using the PSCAD/EMTDC in a power distribution system.

166.6-MHz quarter-wave $$\beta =1$$ superconducting cavities have been adopted for the High Energy Photon Source, a 6-GeV diffraction-limited synchrotron light source currently under construction. A large helium jacket was required to accommodate the enlarged cavity beam pipe for the heavy damping of higher-order modes; the original electric-probe pickup thus becomes inevitably long with unfavorable mechanical properties. Relocated to an existing high-pressure-rinsing port, a magnetic-loop pickup was designed, characterized by low radio-frequency and cryogenic losses and being multipacting-free and insensitive to manufacturing and assembly tolerances. The consequent removal of the original pickup port from the cavity largely simplified the helium jacket fabrication and may also reduce cavity contamination. This paper presents a comprehensive design of a low-loss magnetic-coupling pickup for quarter-wave $$\beta =1$$ superconducting cavities. The design can also be applied to other non-elliptical structures.

The nuclear charge pickup cross sections of $$^{84}\hbox {Kr}$$ on $$\hbox {CH}_{{2}}$$, C, and Al targets are investigated using CR-39 nuclear track detector at the highest energy of 395 MeV/u. The cross sections for H are calculated from those measured on C and $$\hbox {CH}_{{2}}$$ targets. The dependence of the charge pickup cross section on target mass is studied.

Logistics networks are constantly evolving such that new and more varied structures arise and need to be studied. Carriers are aiming for opportunities to save costs by efficient planning. Motivated by this, we define the two-region multi-depot pickup and delivery problem. A region in this setting refers to an area where customers and depots are located. We differentiate two kinds of requests depending on whether their customers are located in the same region or not. Due to geographical characteristics, direct transportation between different regions is considered inefficient and a long-distance transportation mode needs to be used to connect them. Hence, we face a complex problem where interrelated decisions are to be made. We propose a decomposition into three subproblems, which relate to well-known problems in the literature. For solving the global problem, an adaptive large neighborhood search (ALNS) algorithm is developed. The algorithm mixes operators tailored to each of the different decisions of each subproblem. We demonstrate that these operators are efficient when applied to problems of their primal nature. In an extensive computational study, we show that the proposed ALNS dominates alternative ALNS schemes, where subproblems are treated sequentially. A detailed analysis of the solution convergence is provided. The proposed approach is a powerful tool to tackle complex decision problems in large distribution networks.

In order to improve depth extraction accuracy, a method using moving array lenslet technique (MALT) in pickup stage is proposed, which can decrease the depth interval caused by pixelation. In this method, the lenslet array is moved along the horizontal and vertical directions simultaneously for N times in a pitch to get N sets of elemental images. Computational integral imaging reconstruction method for MALT is taken to obtain the slice images of the 3D scene, and the sum modulus (SMD) blur metric is taken on these slice images to achieve the depth information of the 3D scene. Simulation and optical experiments are carried out to verify the feasibility of this method.

Accurately detecting the arrival time of a channel wave in a coal seam is very important for in-seam seismic data processing. The arrival time greatly affects the accuracy of the channel wave inversion and the computed tomography (CT) result. However, because the signal-to-noise ratio of in-seam seismic data is reduced by the long wavelength and strong frequency dispersion, accurately timing the arrival of channel waves is extremely difficult. For this purpose, we propose a method that automatically picks up the arrival time of channel waves based on multi-channel constraints. We first estimate the Jaccard similarity coefficient of two ray paths, then apply it as a weight coefficient for stacking the multichannel dispersion spectra. The reasonableness and effectiveness of the proposed method is verified in an actual data application. Most importantly, the method increases the degree of automation and the pickup precision of the channel-wave arrival time.

This paper deals with a special vehicle routing problem with backhauls where customers may want to receive items from a depot and, at the same time, return items back to the depot. Moreover, time windows are assumed and three-dimensional loading constraints are to be observed, i.e. the items are three-dimensional boxes and packing constraints, e.g. regarding load stability, are to be met. The resulting problem is the vehicle routing problem with simultaneous delivery and pickup (VRPSDP), time windows and three-dimensional loading constraints (3L-VRPSDPTW). This problem occurs, for example, if retail stores are supplied by a central warehouse and wish to return packaging material. A particular challenge of the problem consists of transporting delivery and pickup items simultaneously on the same vehicle. In order to avoid any reloading effort during a tour, we consider two different approaches for loading the vehicles: (i) loading from the back with separation of the loading space into a delivery section and a pickup section and (ii) loading from the (long) side. A hybrid algorithm is proposed for the 3L-VRPSDPTW consisting of an adaptive large neighbourhood search for the routing and different packing heuristics for the loading part of the problem. Extensive numerical experiments are conducted with VRPSDP instances from the literature and newly generated instances for the 3L-VRPSDPTW.

The evaluation of the dirt resistance of organic coatings according to traditional accelerated methods (e.g., the standard method GB/T 9780-2013 in China) usually provides results which deviate from their real-world performance in seriously polluted environments. As an alternative, a novel adsorption method with methyltrimethoxysilane-modified rice-straw ash as the artificial dirt standard was proposed in this paper. With this method, the ash was dispersed into the air in a testing chamber and then allowed to physically adsorb to the coating, which is believed to more accurately simulate the adsorption behavior of floating particulates outdoors. Two groups of latex coatings from Dow Chemical Company were employed to evaluate the adsorption method by monitoring the changes in color, whiteness, and reflectivity. In parallel, outdoor exposure testing of these coatings was conducted. The influences of charging method, of ash type, and panel position on the testing results were carefully investigated. Multicharging of ash (9 g × 3) and parallel panels at different positions in the testing chamber are designed for the generation of repeatable results. It was demonstrated that the adsorption method basically matched the outdoor exposure results and was more predictive of real-world results than GB/T 9780-2013.

This paper deals with the pollution-routing problem with simultaneous pickup and delivery, where the goal is to minimize fuel consumption and emissions by scheduling and routing customers. A nonlinear mix integer programing model is presented for this problem, and an adaptive large neighborhood search heuristic is proposed for the solution method including new removal and insertion operators. Also a heuristic algorithm is proposed to construct the initial solution. The proposed method is validated by computational experiments conducted on two classes of benchmark instances. The experiments further show that our proposed heuristic outperforms related heuristics and improved the results of existing literature.

The rise of ink-jet printing technology has led to numerous studies about functional fluids, which, in most cases, are made to change and improve the chemical and rheological properties. Besides this, there are several patents about the recirculation fluid system that help to prevent settling particles, and thus improving print quality without consequences in the chemical composition of the fluid. This paper presents a dynamic analysis of a recirculation circuit for ink-jet microsystems applications with fluids that contain a particle size of 40 nm to 10 $$\upmu$$μm. This analysis integrates multiple mathematical and experimental models, in regard to variables such as: viscosity change with temperature and solid volume fraction, sedimentation, surface tension and flow behavior. As a result, specific values of vacuum pressure for different drop-on-demand print heads with different ink-jet functional fluids, places of probable sedimentation and minimum pickup velocities to remove settled particles are given.

This paper presents a real-life variable periodic vehicle routing problem (VPVRP) which is originated from an auto parts company. The idea of lean production has been applied in the production of the auto parts manufacturer. The VPVRP consists of the assignment of a pickup schedule for each of its supplier’s locations and also the establishment of daily routes in order to minimize total transportation cost. Since the problem is a special case of the periodic vehicle routing problem, several initial solution algorithms and a hybrid tabu search (HTS) are developed for solving the problem. There are distinctive features in the HTS, including the intensification strategy, the diversification strategy, and the combination of tabu search with the switch mechanism. The computational results show that the proposed initial algorithms and the HTS outperform the current scheduling method used by the case plant with a significant improvement.

Zone 3 of distance relay provides remote backup protection for adjacent transmission lines using local information. At times, zone 3 is prone to maloperation under stressed system conditions, which may cause serious threat to grid security. Zone 3 decisions can be more accurate, if fault pickup information of the adjacent line relays is availed. In this paper, zone 2 pickup signals of adjacent line relays are unified using simple logic gates and the information is transferred to supervise remote backup protection; the zone 3. Proposed method is tested for WSCC nine-bus and two-area four machine systems under different conditions and found to be accurate.

In this paper, we consider two-tiered city logistics systems accounting for both the inbound and outbound traffic, that have not been taken into account in models and algorithms for vehicle routing research. The problem under study, called the Multi-trip Pickup and Delivery Problem with Time Windows and Synchronization, has two sets of intertwined decisions: the routing decisions which determine the sequence of customers visited by each vehicle route, the scheduling decisions which plan movements of vehicles between facilities within time synchronization restrictions. We propose a tabu search algorithm integrating multiple neighborhoods targeted to the decision sets of the problem. To assess the proposed algorithm, tests have been conducted on the first benchmark instances of the problem which have up to 72 facilities and 7200 customer demands. As no previous results are available in the literature for the problem, we also evaluate the performance of the method through comparisons with published results on two simplified problems: the Multi-zone multi-trip vehicle routing problem with separate delivery and collection, and the Vehicle routing problem with backhauls. The proposed algorithm is competitive with existing exact and meta-heuristic methods for these two problems.

A bunch arrival-time monitor (BAM) based on an electro-optical intensity modulation scheme is currently under development at Shanghai Soft X-ray Free-Electron Laser to meet the high-resolution requirements for bunch stability. The BAM uses a radio frequency signal generated by a pickup cavity to modulate the reference laser pulses in an electro-optical intensity modulator (EOM), and the bunch arrival-time information is derived from the amplitude change of the laser pulse after laser pulse modulation. EOM is a key optical component in the BAM system. Through the basic principle analysis of BAM, many parameters of the EOM are observed to affect the measurement resolution of the BAM system. Therefore, a systematic analysis of the EOM is crucial. In this paper, we present two schemes to compare and analyze an EOM and provide a reference for selecting a new version of the EOM.

A liquid marble is a droplet coated with hydrophobic powder. The porous and hydrophobic coating prevents physical contact between the liquid and its surroundings without compromising gas exchange. As such, the liquid marble is an excellent platform for culturing cells. With the promising biomedical applications of the liquid marble, numerous studies have been conducted to improve its handling using magnetism, which limits the liquid marble coating to hydrophobised ferromagnetic materials. In this paper, we propose a novel, simple and cheap method of liquid marble manipulation such as pick and place based on the well-known dielectrophoresis force. Liquid marbles of various volumes were picked up using an electrode with a high voltage bias, moved to a different location and placed intact. This method provides reliable handling to a host of existing non-ferromagnetic liquid marbles without the need to engineer their coatings. Furthermore, this method enables the automation of the liquid marble handling process. This paper provides an empirical relationship to link the pickup force to the experimental parameters.

Beam signals captured from a button-type pickup contain multidimensional information including the bunch charge, transverse position, bunch length, and longitudinal phase. A bunch phase monitor, which retrieves longitudinal phase information from a pickup signal at a bunch-by-bunch rate, has been developed at the Shanghai Synchrotron Radiation Facility. This paper introduces the basic principles, system setup, data processing method, and preliminary experimental results of this system. The systematic measurement error introduced by the limited system bandwidth, bunch length, and bunch charge variation was studied using simulation data. The random measurement uncertainty was evaluated using experimental beam data. The experimental result shows that the longitudinal phase resolution of this system is better than 1.0 ps. The first application, measuring the relationship between the longitudinal phase and bunch charge to determine the energy loss factor, was implemented, and the preliminary result is also discussed.

The process of deceleration of the solar wind downstream of the termination shock is studied on the basis of a one-dimensional multi-component model. It is assumed that the solar wind consists of thermal protons, electrons and interstellar pickup protons. The protons interact with interstellar hydrogen atoms by charge-exchange. Two cases are considered. In the first one, the charge-exchange cross-section for thermal protons and hydrogen atoms is the same as for pickup protons and atoms. Under this condition, there is a strong dependence of the solar wind velocity on the downstream temperature of pickup protons. When the proton temperature is close to 10 keV, the change in the velocity with the distance from the termination shock is similar to that measured on the Voyager 1 spacecraft: linear velocity decrease is accompanied by an extended transition region with near-zero velocity. However, with a more careful approach to the choice of the charge-exchange cross-section, the situation changes dramatically. The strong dependence of the solar wind speed on the pickup proton temperature disappears and the transition region in the heliosheath disappears as well, at least at reasonable distances from the TS.

We studied the effect of bias voltage between slider and disk surfaces to reduce lubricant pickup by the slider. A perfluoropolyether (PFPE) lubricant film, which is coated on the disk surface, has been considered to be charged to a negative voltage by the airflow on the rotational disk surface. Because the PFPE lubricant film is negatively charged, the lubricant pickup should be reduced by a bias voltage with a negative voltage on the slider surface. We confirmed changes in the lubricant pickup in a lubricant pickup test conducted at different bias voltages. A positive voltage of the slider accelerated the lubricant pickup, whereas a negative voltage reduced it.

The SuperCDMS collaboration is moving forward with the design and construction of SuperCDMS SNOLAB, where the initial deployment will include $$\sim $$ 30 kg of Ge and $$\sim $$ 5 kg of Si detectors. Here, we will discuss the associated cryogenic cold hardware required for the detector readout. The phonon signals will be read out with superconducting quantum interference device arrays and the ionization signals will use high electron mobility transistor amplifiers operating at 4 K. A number of design challenges exist regarding the required wiring complex impedance, noise pickup, vibration, and thermal isolation. Our progress to date will be presented.

The anti-corrosive metal coatings on ferromagnetic tubes are the important components in power plants and need non-destructive evaluation (NDE) techniques to measure their thickness precisely. The objective of this research is to develop pulsed eddy current (PEC) technique for measuring the coating thickness accurately. PEC signals are investigated for the evaluation of coating thickness using a differential PEC probe, which consists of a driving coil and two pickup coils. The characteristics of PEC signals for coating thickness variations show that the related features, such as the time-to-peak and peak value, change linearly with thickness change. A new feature, called as time to the rising point, related to the propagation time of electromagnetic field in conductive metals is adopted for coating thickness measurement. These features can be used to inspect the coating thickness within the accuracy of 0.02 mm.

This paper investigates perturbation operators for variable neighborhood search (VNS) approaches for two related problems, namely the pickup and delivery traveling salesman problem with LIFO loading (TSPPDL) and FIFO loading (TSPPDF). Our study is motivated by the fact that previously published results on VNS approaches on the TSPPDL suggest that the perturbation operation has the most significant effect on solution quality. We propose a new perturbation operator for the TSPPDL that achieves better results on average than the existing best approach. We also devise new perturbation operators for the TSPPDF that combine request removal and request insertion operations, and investigate which combination of request removal and request insertion operations produces the best results. Our resultant VNS that employs our best perturbation operator outperforms the best existing TSPPDF approach on benchmark test data.

Laboratory experiments were conducted to measure sediment pickup rate over two-dimensional fixed dunes. Measurements were performed over both stoss and lee sides of the dune with sediments of D 50 = 0.23, 0.44 and 0.86 mm. Flow velocity and turbulence were also measured by using an acoustic Doppler velocimeter. By analysing the experimental data, an empirical sediment pickup function based on depth-averaged flow parameters was proposed to estimate the pickup rate over the dune.

We introduce a low-cost and effective technique that can transform waste cement-based dust into a superhydrophobic coating with dirt pickup resistance. An organic-inorganic hybrid superhydrophobic coating is prepared by the sol-gel method using methyltriethoxysilane as a precursor and waste cement-based dust as a film-forming material. Orthogonal experiments and a comprehensive scoring method were used to optimize the composition and production technologies. Our results show that this superhydrophobic organic-inorganic hybrid coating has an average static contact angle of 151.65° and low water adhesion. Related tests reveal that the dirt pickup resistance, washing resistance and film-substrate cohesion of this coating are also outstanding. The multi-scale physical and chemical mechanisms behind the properties of the coating are investigated. This recycled cement-based coating can be used as the external cover of engineering structures to protect them from corrosion.

Not only can polarized 3He gas work as neutron spin filters (NSF) but also search for spin-dependent new interactions beyond the standard model. For both cases, the relative polarization of the spin polarized noble gas needs to be measured precisely. Various NMR techniques are applied practically to monitor the 3He cell’s polarization. In this work, we tried to optimize the pickup coil for the spin exchange optical pump (SEOP) based 3He system. By optimizing the signal-to-noise ratio (SNR), we found that the coil should be wound by thin wire for a higher number of turns. The optimized sizes of the pickup coils depend on the detailed configurations. For a spherical 3He cell with radius a, we found the optimized coil radius is $\sqrt{5}(a+d)$ , where d is the coil to cell surface distance. For a cylindrical 3He cell with height h, for the configurations where the coils were placed either along or perpendicular to the longitudinal axis of the target cell, we derived the optimized sizes for the specific configurations. We believe these results are practically useful for designing pickup coils of polarized 3He systems.

The era of big data has necessitated the use of ultra-high density optical storage devices. Super-resolution near-field structure (super-RENS), which has successfully surpassed the fundamental optical diffraction limit, is one of the promising next generation high-density optical storage technologies. This technology combines the traditional super-resolution optical disk with a near-field structure, and has the advantages of structural simplicity, strong practicability, and, more importantly, compatibility with the current optical storage pickup. The mask layer in super-RENS functions as the key to realizing super- resolution. Development of suitable materials and stack designs has greatly been improved in the last decade. This paper described several types of super-RENS, such as aperture-type, light scattering center-type, bubble-type, and other types (e.g., WOx and ZnO), particularly the newly proposed super-RENS technology and research achievements. The paper also reviews the applications of super-RENS in high-density optical data storage in recent years. After analyzing and comparing various types of super-RENS technology, the paper proposes the aperture- type based on the mechanism of nonlinear optics as the most suitable candidate for practical applications in the near future.

Magnetic fields due to neuronal currents inside the brain have been modeled as arising due to a current dipole positioned in a thin hemispherical shell. Magnetic signals due to this current dipole at measurement locations, as sensed by an array of superconducting first order axial gradiometric pickup loops distributed uniformly in a concentric shell above scalp, have been simulated. The difference in the simulated magnetic field between two loops constituting the axial gradiometer is represented in terms of an infinite series expansion based on spherical harmonics. The external magnetic noise has been modeled as a magnetic dipole and is represented by another set of terms in infinite series expansion based on spherical harmonics. The block matrix inversion has been utilized to extract the magnetic signal due to neuronal currents rejecting the unwanted external magnetic noise from total simulated signal from a set of 64 gradiometers using signal space separation method. This rejection of the strong external magnetic noise has also been demonstrated using block-matrix inversion for sources of external magnetic noise with radial position as close as 0.4 m.

International audience; A carrier collaboration problem with pickup and delivery requests is considered, in which multiple carriers form an alliance to share their pickup and delivery requests and vehicle capacities in order to reduce their transportation costs and consequently increase their profits. A multi-round pricing-setting based combinatorial auction approach is proposed to solve the problem. In each round of the auction, the auctioneer updates the price for serving each request based on Lagrangian relaxation, and each carrier, who is a bidder, determines its requests to be outsourced and the requests to be acquired from other carriers by solving a request selection problem based on the prices. Different price adjustment methods are proposed and compared. Numerical experiments on randomly generated instances demonstrate the effectiveness of the approach.

The growing cost of transportation and distribution pushes companies, especially small and medium transportation enterprises, to form partnership and to exploit economies of scale. On the other hand, to increase their competitiveness on the market, companies are asked to consider preferences of the customers as well. Therefore, tools for logistics management need to manage collective resources, as many depots and heterogeneous fleets, providing flexible preference handling at the same time. In this paper we tackle a pickup and delivery vehicle routing problem involving such aspects; customers place preferences on visiting time (represented as soft time windows), and their violation is allowed at a price. Our interest in this problem stems from an ongoing industrial project. First we propose an exact branch-and-price algorithm, having as a core advanced dynamic programming techniques. Then we analyze through a computational campaign the impact of soft time windows management on the optimal solution in terms of both routing and overall distribution costs. Our experiments show that our approach can solve instances of real size, and clarify the practical usefulness of soft time windows management.

In this study, a thickness and refractive index measuring system for the transparent plate has been proposed. The measuring system is composed of an astigmatic measurement module and a light spot measurement module using a DVD optical pickup, a laser diode and a quadrant photodiode detector. Both of the thickness and refractive index of a transparent plate are converted into the focusing error of DVD pickup based on astigmatic method and the light spot displacements based on snell’s law in our proposed system. The thickness and the refractive index are simultaneously calculated by means of two nonlinear formulas. The accuracy of the proposed system is 99 % verified by a height Gauge and the refractive index by the TF-166.

The vehicle routing problem with deliveries and pickups is one of the main problems within reverse logistics. This paper focuses on an important assumption that divides the literature on the topic, namely the restriction that all deliveries must be completed before pickups can be made. A generalised model is presented, together with a mathematical formulation and its resolution. The latter is carried out by adopting a suitable implementation of the reactive tabu search metaheuristic. Results show that significant savings can be achieved by allowing a mixture of delivery and pickup loads on-board and yet not incurring delays and driver inconvenience.