Load Splitting Research Articles

A gradient-descent-based framework for solving a stochastic two-echelon delivery problem with cargo-bikes

In this paper, we examine a stochastic two-echelon vehicle routing problem (2e-VRP) using cargo bikes within hyperconnected networks. The focus is on the integration of both delivery and pickup of reusable containers, incorporating transshipment operations, time windows, and stochastic demand constraints. The model also considers the flow consolidation for empty and full containers at the satellites and allows for load splitting. Moreover, this study introduces an innovative gradient-descent-based optimization framework to handle the combinatorial complexity of the proposed model, opening new avenues in stochastic programming. Furthermore, the performance of this novel method is compared against the sample average approximation method, evaluating both solution quality and computational efficiency. Experimental results demonstrate the model’s advanced integration and flexibility, significantly enhancing urban delivery systems and advancing logistics and transportation optimization research.

Experimental investigation and soft bond modelling analysis on mechanical behaviours of foamed polyurethane solidified ballast

Polyurethane solidified ballasted track (PSBT) offers a novel solution to the frequent maintenance requirements of ballasted track, delivering a high-quality track infrastructure. In this study, laboratory tests were carried out on polyurethane solidified ballast (PSB) specimens under compression, tensile and shear conditions to obtain stress-strain curves and deformation characteristics. The numerical model of the PSB specimens was developed based on the discrete element method (DEM). The effects of the parameters related to the bond elongation on the tensile and compressive properties of the PSB specimens were analysed, and the parameters were calibrated by the test results. The results showed that the compressive, tensile and shear strengths of the specimens increased with increasing polyurethane foam density. During uniaxial and split loading, the stress-strain curves of the PSB specimens gradually entered the stress softening stage after an elastic phase. The compressive-tensile strength ratio of the specimens was around 1.55. From the perspective of deformation, the PSB specimen is primarily strained by the highly compressible polyurethane materials, and the specimen generates a considerable residual strain at the initial stage of cyclic loading. Thus, it is necessary to pre-compress the PSB to achieve an optimal load-bearing condition. DEM simulations show that there is a strong correlation between the mesoscale bond elongation of particles and the macroscopic tensile and compressive strengths of the specimens. It is therefore possible to utilise a high value of bond elongation to simulate bonded granular materials with low compressive-tensile strength ratios. The results obtained from the simulation of the numerical method used in this study are in high agreement with the test, which provides a new idea for revealing the meso- and macro- mechanical properties of PSB and its application in PSBT.

Dynamic failure behaviour of sandstone with filling joints using the Brazilian disc method

Rock masses contain joints often filled with low-strength materials such as mud and gum. The instability mechanism of a filled jointed rock mass under dynamic loads is complex, posing challenges for disaster control. Splitting tests were conducted using a split Hopkinson pressure bar device and a high-speed camera to investigate the effects of weak-filling joints at various angles on the failure mechanism and mechanical properties of sandstone. The typical failure processes, splitting mechanical properties and fracture morphologies were analysed. The results indicated that as the joint angle increased from 0 to 90°, the crack coalescence pattern of the jointed sample under static and dynamic splitting loads evolved from complete separation along the bonding surfaces to shear–slippage failure along the direction of the joint angle and tensile–shear failure with a dominant zigzag track, ultimately leading to typical tensile failure. Under dynamic loads, filled joints reduced the brittleness of the samples, contrary to the behaviour observed under static loads. The peak load and displacement were proportional to the joint angle and impact gas pressure, respectively. The fracture surface morphology precisely reflected the macroscopic fracture mechanism at the microscopic scale.

Evolution mechanism of hydraulic fracture in concrete under dynamic loading

The influence of hydraulic loading within cracks on the evolution mechanism of concrete under dynamic loading was investigated in this paper. Several strain gauges were employed to stick along the crack tip during the experiments. The moving crack tip was captured using these gauges during fracture. In particular, during the stable cracking stage, consistent propagating crack-tip speeds were observed under varying water pressures. Initially, the measured speed measured 2.0 m/s, which later increased to 20.0 m/s. Based on hydraulic experiments, a relationship between the crack tip and the water front was established, allowing the derivation of pressure distribution within crack from experimental data collected under dynamic loading conditions. Furthermore, the fracture parameters, including initial toughness, critical toughness, and cohesive toughness, were calculated for concrete subjected to split loading. The cohesive toughness experienced a 13.9% reduction with the increasing hydraulic pressure to 0.4 MPa, highlighting the deterioration of cohesive fracture toughness due to water infiltration within the concrete crack. This study provides insights to improve the design of civil and hydraulic engineering structures, such as gravity dams.

Fastmove: A Comprehensive Study of On-Chip DMA and its Demonstration for Accelerating Data Movement in NVM-based Storage Systems

Data-intensive applications executing on NVM-based storage systems experience serious bottlenecks when moving data between DRAM and NVM. We advocate for the use of the long-existing but recently neglected on-chip DMA to expedite data movement with three contributions. First, we explore new latency-oriented optimization directions, driven by a comprehensive DMA study, to design a high-performance DMA module, which significantly lowers the I/O size threshold to observe benefits. Second, we propose a new data movement engine, Fastmove , that coordinates the use of the DMA along with the CPU with DDIO-aware strategies, judicious scheduling and load splitting such that the DMA’s limitations are compensated, and the overall gains are maximized. Finally, with a general kernel-based design, simple APIs, and DAX file system integration, Fastmove allows applications to transparently exploit the DMA and its new features without code change. We run three data-intensive applications MySQL, GraphWalker, and Filebench atop NOVA , ext4-DAX , and XFS-DAX , with standard benchmarks like TPC-C, and popular graph algorithms like PageRank. Across single- and multi-socket settings, compared to the conventional CPU-only NVM accesses, Fastmove introduces to TPC-C with MySQL 1.13-2.16 × speedups of peak throughput, reduces the average latency by 17.7-60.8%, and saves 37.1-68.9% CPU usage spent in data movement. It also shortens the execution time of graph algorithms with GraphWalker by 39.7-53.4%, and introduces 1.01-1.48 × throughput speedups for Filebench.

Impact of a Divided Phenobarbital Load and Taper Compared With Lorazepam Symptom Triggered Therapy in Hospitalized Patients.

Benzodiazepines are the preferred treatment for alcohol withdrawal. Phenobarbital is an alternative in the setting of prescriber expertise or benzodiazepine contraindication. To evaluate the efficacy and safety of a phenobarbital dosing strategy aimed at treating a spectrum of alcohol withdrawal symptoms across various patient populations. Retrospective review of patients admitted with concerns of alcohol withdrawal between May 2018 and November 2022. Patients were separated into a before-after cohort of lorazepam or phenobarbital. The primary outcome was hospital length of stay (LOS). Secondary outcomes were intensive care unit (ICU) LOS, escalation of respiratory support, increased level of care (LOC), and incidence of delirium tremens and/or seizures. Two hundred and seventy-seven patients received lorazepam and 198 received phenobarbital. Hospital LOS was longer in the phenobarbital cohort compared with the lorazepam cohort (6.9 vs 9.3 days). There was no difference in ICU LOS. Level of care increases were fewer in the phenobarbital cohort (4 events vs 19 events). There were higher rates of non-invasive respiratory interventions in the lorazepam cohort and higher rates of mechanical ventilation in the phenobarbital cohort. Utilization of phenobarbital was attributed to a reduction in delirium tremens and seizures. This study is novel because of the broad application of a phenobarbital order set across multiple levels of care and patient admission diagnoses. A risk targeted split load intravenous phenobarbital order set can safely be administered to patients with fewer escalations of care, seizures, delirium tremens, and respiratory care escalation.

Vehicle routing problem simultaneous deliveries and pickups with split loads and time windows with genetic algorithm (case study in shipping company)

Vehicle routing problem simultaneous deliveries and pickups with split loads and time windows with genetic algorithm (case study in shipping company)

Experimental and numerical study of disk specimen with rough structural plane under splitting test

To study the effects of the anisotropic matrix and structural planes on the splitting strength and failure mode of rocks, Brazilian splitting tests were carried out with seven different loading angles on specimens of rock-like materials with rough structural planes. The surface strains of the samples during the failure process were monitored and analysed with the help of a high-speed camera and digital image correlation (DIC) technology. The test results showed that the Brazilian splitting strength (BSS) decreased gradually with an increased loading angle. According to the crack morphology, the samples showed three failure modes, and the structural plane and the loading angle (θ) had an important effect on the failure mode. When θ < 75°, the sample failure was mainly affected by the matrix, and when θ > 75°, the sample failure was mainly controlled by the structural plane. The numerical simulation of the sample with a structural plane was carried out by the PFC2D particle flow program, the micro parameters were calibrated using a back propagation (BP) neural network model. The internal cracks of the sample under a splitting load were mainly matrix tensile microcracks and structural plane shear microcracks, and the tensile microcracks in the side with the weak matrix appeared significantly earlier than those in the side with the strong matrix. With increasing loading angle, the proportion of tensile microcracks in the matrix increased, while the proportion of shear microcracks in the matrix decreased, especially in the weak matrix. The microcracks at the structural plane mainly changed from tensile microcracks to shear microcracks, and the development degree of microcracks along the structural plane was more significant than that on the weak matrix with increasing loading angle. The results of the study can provide a reference for rock stability evaluation and utilization.

Particle flow simulation of Brazilian splitting failure characteristics of layered shale

Shale reservoir is the research hotspot in the development of unconventional oil and gas resources. The properties of bedding plane have an important influence on the mechanical behavior of shale. According to the fracture characteristics of layered shale under Brazilian splitting load, the effects of bedding angle, bond strength ratio and natural fractures on the tensile strength and fracture pattern of layered shale in Brazilian splitting test were studied by particle flow code. The evolution mechanism of meso–macro fracture of shale is analyzed by combining the dynamic change process of particle mesoscopic force chain and crack. The results show that three types of fracture patterns are observed: splitting tensile failure of shale matrix, splitting tensile failure along bedding plane and tensile–shear composite failure along shale matrix and bedding plane. Mesoscopic cracks initiate at the top and bottom loading points of the disk. After the peak load, mesoscopic cracks propagate through and appear dense force chains until macroscopic failure occurs. The bond strength ratio of bedding plane affects the failure pattern and peak strength of the specimen. With the increase in bedding angle, the tensile strength decreases gradually. Considering the influence of natural fractures, the tensile strength of shale is lower, and the crack propagation is more complex. The research model and results provide theoretical basis for the mechanical properties evaluation and fracture pattern analysis of shale.

Customised bus route design with passenger-to-station assignment optimisation

As an emerging and innovative public transportation mode, the customised bus (CB) has drawn widespread attention. Existing studies of the CB mainly focus on issues regarding the bus station location, route design, timetabling, and fare setting, but rarely consider the passenger to bus station assignment problem which can significantly influence passengers’ benefit and the buses’ operating scheme. Thus, this study focuses on the customised bus routing problem with passenger-to-station assignment (CBRP-PSA) aiming to simultaneously minimise passengers’ CB service access cost and the bus route cost. A time-discretized multi-commodity network flow model is developed to jointly determine the CB routes, timetables, and passenger-to-station assignment by allowing split loads and mixed loads. Through the dualization, the developed model is decomposed into two solvable sub-problems, and a Lagrangian-based heuristic solution algorithm is proposed. The model and algorithm are implemented in illustrative, medium-scale, and large-scale transportation networks to demonstrate their effectiveness under different scenarios.

Analisis Pemecahan Beban Penyulang Kalipare 20 kV

The Kalipare feeder is a feeder located at PT PLN (Persero) ULP Sumberpucung where the feeder has a feeder length of 232.9 kms and a load of 161.8 A, with a voltage drop of 17.981 kV, the energy loss that is not channeled in 40.82 minutes is IDR 5,333,734.00. So with that the feeder is carried out there is a splitting of the load into two, namely 86.6 A and 74.4 A, with the end voltage being 19.27 kV, with the energy loss that is not channeled in 40.82 minutes is Rp. 2,454.510.8. This load solving is carried out based on the existing conditions of the Kalipare Feeder in 2019, as well as modeling in the form of simulations using ETAP 12.6 and analyzing the simulation results with the existing load breaking conditions in 2020. Load splitting locations are carried out at 7 points taking into account the value of the investment to be made used to do the job. The locations where the load splitting will be carried out are GI Karangkates, Perempatan Peteng, Tumpakmiri, Kalipare, and Banduarjo with an investment cost of Rp. 21,124,247,696 with the construction of 527 gates. After breaking the load, which resulted in the Kalipare feeder and the Donomulyo feeder, the value of the voltage drop on the Kalipare feeder decreased to 18.25 kV; 8.70%, while the Donomulyo Feeder is 19.241 kV; 3.84%. The solution to the load of the Kalipare feeder will minimize losses due to blackouts and increase customer satisfaction.

Branch-and-Price-and-Cut for the Heterogeneous Fleet and Multi-Depot Static Bike Rebalancing Problem with Split Load

Heterogeneous Fleet and Multi-Depot Static Bike Rebalancing Problem with Split Load (HFMDSBRP-SD) is an extension of the Static Bike Rebalancing Problem, considering heterogeneous fleet multiple depots, allowing split load. It consists of finding a set of least-cost repositioning vehicle routes and determining each station’s pickup or delivery quantity to satisfy the demand of each station. We develop a branch-and-price-and-cut (BPC) where a tabu search column generator and a heuristic label-setting algorithm are introduced to accelerate the column generation procedure, the subset-row (SR) inequalities, the strong minimum number of vehicles (SMV) inequalities, and the enhanced elementary inequalities are extended fitting this problem and applied to speed up the global convergence rate. Computational results demonstrate the effectiveness of the BPC algorithm. Among 360 instances with a maximum size of 30, there are 298 instances capable of achieving optimality within two hour time limitation.

STUDI PEMECAHAN PENYULANG OMBILIN UNTUK PERBAIKAN DROP TEGANGAN DI PT PLN (PERSERO) RAYON PADANG PANJANG MENGGUNAKAN APLIKASI ETAP

Ombilin feeder is one of the longest feeders in PT. PLN (Persero) Rayon Padang Panjang. The total length of the medium voltage network is 117.116 Kms. With a large load, the length of the network and the cross-sectional area vary, causing a voltage drop in the feeder. According to SPLN 72:1987 the allowable voltage drop is 5%. Therefore, a solution is needed to reduce the voltage drop on the feeder to comply with PLN standards. One of them is by changing the load splitting. The loading pattern was changed by optimizing the cross-sectional area of the 240 mm2 AAAC wire which has a better KHA and a smaller impedance. To analyze and find out how much improvement the voltage drop is before and after the load splitting is done, a simulation is carried out using the ETAP 12.6 software. Based on the simulation results, the voltage drop before breaking the load in Baing is 6.67% with a voltage value of 19.413 KV and in Simawang data it is 6.71% with a terminal voltage value of 19.404 kV. After breaking the load, the voltage drop in Baing is 4.19% with a voltage value of 19.929 KV and in Data Simawang it is 4.23% with a terminal voltage value of 19.921 kV. Based on these results, the cause of the voltage drop is influenced by several things, namely the current flowing in the channel, the distance and cross-sectional area of the conductor used.Keywords: Load, Voltage Drop, ETAP.

Mathematical models for a ship routing problem with a small number of ports on a route

This paper presents an industrial ship routing problem with split loads faced by a steel company that exports its steel products to neighboring countries. The problem considers two types of ships: ships with contracts of affreightment and spot ships. It also considers other practical constraints, such as cargo–cargo and cargo–ship compatibility and the minimum loading amount for using a ship. Due to high surcharges for multiple port visits, each ship is allowed to visit at most two loading and two unloading ports. Herein, arc flow-based and path flow-based mathematical models are proposed to solve the problem. Computational experiments show that the path flow model is more efficient than the arc flow model. The path flow model can reduce the computational time by 67% on average and find optimal solutions to real-world ship routing problems in acceptable computational time in most cases.

Exact algorithms for the multiple depot vehicle scheduling problem with heterogeneous vehicles, split loads and toll-by-weight scheme

We study a general version of the multiple depot vehicle scheduling problem, which is motivated by the practice of line-haul transportation in Chinese express delivery firms. In this problem, there are a set of trips to be served by a fleet of vehicles. Each trip has a certain amount of packages to be transported from an origin to a destination. Each vehicle can serve a sequence of trips, but it has to depart from and return to its base depot. We aim at assigning trips to vehicles such that all trips are fully served and the total transportation cost is minimized. This problem is general because several practical features have been considered, including heterogeneous vehicles, service time windows, split loads, and the toll-by-weight scheme. These features greatly broaden the applicability of this problem, but at the price of complicating it. We first formulate this problem into a nonlinear route based model, and then equivalently transform it into a linear route-cover based model. To solve the model, we propose two exact algorithms, namely, a branch-and-price and a branch-and-benders decomposition. Both algorithms are built upon a branch-and-bound framework. Particularly, we design a column generation procedure equipped with an efficient label setting method to solve subproblems involved in the two algorithms. Computational experiments are conducted on a set of random instances, and the results have substantiated the effectiveness and efficiency of our model and algorithms.

Design and simulation of DC distributed power supply with power balance control technique

This paper presents the analysis, design and simulation of DC distributed power supply controlled with power and energy balance control technique. The proposed system consists of 5 connection structures of DC to DC converters which are parallel, cascade, source splitting, load splitting, and stack. The system mathematical model is analyzed by the average small-signal method. The proposed power balance control technique is used in the instance where the main sources supply the load of the system. The energy balance control technique is used in the case that the load at the 24 V and 12 V bus is backed up with a battery. The DC Distributed system is simulated by MATLAB/Simulink. The system has 1 kW power rating and contains 6 voltage bus with voltage ratings of 380, 100, 60, 48, 24, and 12 V. The simulation results show that, with the proposed power balance design and control technique, the system provides good dynamic responses and stability. In addition, the proposed technique simplifies the parameter design of the PI controller and solves the basic control limitations of the DC to DC converter.

A heuristic algorithm for optimal load splitting in hybrid thermally activated building systems

Thermally activated building systems (TABS) integrate high thermal inertia into the heating and cooling system, which has advantages and disadvantages. During sudden fluctuations and high peaks in the energy demand of a building, the thermal comfort may not be efficiently maintained by TABS due to its slow reaction to the control signals. Thus, one solution is to add a complementary fast-reacting emission system to offset the peak loads and guarantee thermal comfort. Conversely, the high thermal inertia of TABS offers peak-shaving and load-shifting opportunities. By optimally exploiting the high thermal inertia of TABS, significant downsizing of the production system can be achieved. Thus, the dynamic behavior of the TABS must be incorporated into the design procedure. Furthermore, the optimal load split between the TABS and the secondary system is a key design consideration. This study reviews the reasons why an appropriate design methodology is not currently available. Moreover, an optimal load splitting algorithm (OLSA) is proposed as a solution, and its performance was verified against a baseline scenario by applying it to nine case studies. The results demonstrate that the OLSA estimated the optimal load split with a maximum error of 9.6%. The application of the OLSA as an easy-to-use tool for the designer was also illustrated. Additionally, the OLSA provided a significant downsizing of the components in the early-stage design (45% in cooling and 38% in heating).

Metaheuristic, models and software for the heterogeneous fleet pickup and delivery problem with split loads

This paper addresses a rich variant of the vehicle routing problem (VRP) that involves pickup and delivery activities, customer time windows, heterogeneous fleet, multiple products and the possibility of splitting a customer demand among several routes. This variant generalizes traditional VRP variants by incorporating features that are commonly found in practice. We present two mixed-integer programming models and propose a metaheuristic based on Adaptive Large Neighborhood Search for the addressed problem. Additionally, to facilitate the use of the proposed approaches in real-world decision-making, we develop an open-source, publicly available web interface that allows one to set and solve VRP variants with the mentioned features. Computational experiments using benchmark instances with up to 150 customers show that the approaches can be used to obtain good-quality solutions in a reasonable time frame in practice.

Dynamic splitting behaviour of ultra-high-performance concrete confined with carbon-fibre-reinforced polymer

Fibre-reinforced polymer (FRP) wrapping is highly effective in enhancing the compressive properties of concrete. However, the dynamic splitting performance of FRP-confined ultra-high-performance concrete (UHPC) remains unexplored. This study investigated the impact resistance of carbon FRP (CFRP)-confined UHPC under splitting loads. The UHPC cylinders were wrapped in CFRP jackets of thicknesses from one to three plies. Several impact tests were conducted using a Ø100mm split Hopkinson pressure bar apparatus at different strain rates ranging from 2 s−1 to 17 s−1. The dynamic behaviours of the specimens were investigated and compared with those under quasi-static loading. The results indicated that the splitting properties of UHPC exhibited a strong strain-rate dependency; however, the confinement of CFRP reduced the strain-rate sensitivity of UHPC. The rupture of the CFRP following UHPC cracking governed the failure of CFRP-confined UHPC under dynamic splitting loads. Although the quasi-static splitting tensile strength could be improved approximately linearly by the CFRP confinement ratio, the CFRP confinement effect decreased with increasing strain rate. A new model that considers the effects of confinement ratio and core concrete inertia is proposed to predict the splitting tensile strength of CFRP-confined UHPC under impact loading.

Research on dynamic splitting damage characteristics and constitutive model of basalt fiber reinforced concrete based on acoustic emission

In order to effectively utilize fiber reinforced concrete in engineering, it is necessary to investigate its mechanical properties and damage characteristics under dynamic tensile loads. This paper studied the effects of loading rate and fiber content on the tensile strength and acoustic emission (AE) characteristics of basalt fiber reinforced concrete (BFRC) in dynamic splitting tests. Brazilian disc splitting tests were carried out on the BFRC specimens with various fiber volume fraction (0%, 0.05%, 0.1%, 0.15%, 0.2%). Then the dynamic splitting AE characteristics were analyzed by means of parameter analysis method. Additionally, the stress–strain curves of BFRC were fitted by the constitutive model modified based on AE rate-process theory. The test results indicate that the tensile strength is enhanced with the increasing loading rate while adding basalt fibers has the same effect. Preferable fiber contents are 0.1% and 0.15%. Then it is found that loading rate and fiber content exert considerable impacts on the AE characteristics. Furthermore, the good fitting results suggest that the mechanics behavior of BFRC under dynamic splitting loads can be well described by the modified constitutive model.