1,317 research outputs found
Optimised solutions to the last-mile delivery problem in London using a combination of walking and driving
Inspired by actual parcel delivery operations in London, this paper describes a two-echelon distribution system that combines the use of driving and walking as part of last-mile deliveries in urban areas for a single driver. The paper presents an optimisation model that explicitly treats and integrates the driving and walking elements, and describes a branch-and-cut algorithm that uses new valid inequalities specifically tailored for the problem at hand. Computational
results based on real instances obtained from a courier operating in London are presented to show the performance of the algorithm
Voxel-Based Solution Approaches to the Three-Dimensional Irregular Packing Problem
Research on the three-dimensional (3D) packing problem has largely focused on packing boxes for the transportation of goods. As a result, there has been little focus on packing irregular shapes in the operational research literature. New technologies have raised the practical importance of 3D irregular packing problems and the need for efficient solutions. In this work, we address the variant of the problem where the aim is to place a set of 3D irregular items in a container, while minimizing the container height, analogous to the strip packing problem. In order to solve this problem, we need to address two critical components; efficient computation of the geometry and finding high-quality solutions. In this work, we explore the potential of voxels, the 3D equivalent of pixels, as the geometric representation of the irregular items. In this discretised space, we develop a geometric tool that extends the concept of the nofit polygon to the 3D case. This enables us to provide an integer linear programming formulation for this problem that can solve some small instances. For practical size problems, we design metaheuristic optimisation approaches. Because the literature is limited, we introduce new benchmark instances. Some are randomly generated and some represent realistic models from the additive manufacturing area. Our results on the literature benchmark data and on our new instances show that our metaheuristic techniques achieve the best known solutions for a wide variety of problems in practical computation times
Collaborative Parcels Logistics via the Carrier’s Carrier Operating Model
Parcel logistics in urban areas are characterized by many carriers undertaking similar activity patterns at the same times of day. Using substantial carrier manifest datasets, this paper demonstrates advantages from rival carriers collaborating using a “carrier’s carrier” operating model for their last-mile parcel logistics operations. Under these circumstances, a single carrier undertakes all the deliveries within a defined area on behalf of the carriers instead of them working independently. Modelling the daily delivery activity of five parcel carriers working over a 3.7 km2 area of central London, comprising around 3000 items being delivered to around 900 delivery locations, and consolidating their activity through a single carrier suggested that time, distance and associated vehicle emissions savings of around 60% could be achieved over the current business-as-usual operation. This equated to a reduction in the number of delivery vans and drivers needed from 33 to 13, with annual savings of 39,425 h, 176,324 km driven, 52,721 kg CO2 and 56.4 kg NOx. Reliance on vans and associated vehicle emissions could be reduced further by using cargo cycles alongside vans for the last-mile delivery, with estimated annual emissions savings increasing to 72,572 kg CO2 and 77.7 kg NOx. The results indicated that consolidation of items for delivery in this way would be especially beneficial to business-to-consumer (B2C) carriers whose parcel profiles comprise relatively small and light items. One of the key barriers to the wider take up of such services by individual carriers is the loss of individual brand identity that can result from operating through a carrier’s carrier
A theoretical model for tellurite-sulfates NaCu(TeO)(SO)(OH) and KCu(TeO)(SO)(OH)
A theoretical model for two new tellurite-sulfates, namely
NaCu(TeO)(SO)(OH) and KCu(TeO)(SO)
(OH) is determined to be compatible with ab-initio calculations. The
results obtained in this work show that some previous speculations in the
literature about the couplings are correct, obtaining a model with a mixture of
ferromagnetic and antiferromagnetic couplings. We use a combination of
numerical techniques to study the magnetic properties of the model. Our
numerical calculations based on the density-matrix renormalization group method
reveal that the system presents Ising-like magnetization plateaux at rational
values of the saturation magnetization.Comment: 7 pages, 8 figure
Quantifying environmental and financial benefits of using porters and cycle couriers for last-mile parcel delivery
Parcel carriers face increasingly difficult operating conditions in busy metropolitan areas due to growing consumer demand for ever faster delivery services and having to cope with traffic congestion and city authority measures that may restrict or penalise access for certain types of vehicle. This paper evaluates the potential environmental and financial benefits of switching from traditional van-based deliveries to an alternative operating model, where porters or cycle couriers undertake deliveries supported by a substantially reduced van fleet.
Results using a specially-developed algorithm to model operations of a real carrier in an area of central London, UK, suggested that the carrier could reduce CO2 emissions by 45%, NOx emissions by 33%, driving distance by 78% and curbside parking time by 45%. Overall cost savings to the carrier were estimated to be in the range 34–39%. Scaling up the modelled emissions savings to London’s Central Activities Zone, an area of approximately 30 km2 and with current total annual parcel delivery distance of around 15 million km, could see annual emissions savings in the region of 2 million kg CO2 and 1633 kg NOx if all carriers utilised porters or cycle couriers. The key operating challenges identified were related to sorting and consolidating items by weight and volume, parcel handover arrangements and how to deal with express items and failed deliveries
S.6.1 β-catenin is a central mediator in SSc
Background. β-catenin is the central integrator of canonical Wnt signalling. Since recent evidence suggests a central role of Wnts in fibrosis, we examined the β-catenin/Wnt pathway in SSc and focused on the role of β-catenin in fibroblast activation. Methods. We performed qPCR for several Wnt ligands and axin-2 to examine Wnt expression in SSc skin. We further studied protein levels of Wnt-1, -4, -10b and β-catenin by IHC. To establish the effects of β-catenin/Wnt signalling on collagen release, we created mice with fibroblast-specific stabilization of β-catenin (dEx3 β-catenin (wt/fl) × Col1a2; Cre-ER) as well as mice carrying fibroblast-specific deletion of β-catenin [Ctnnb1(fl/fl) × Col1a2; Cre-ER]. Summary of the results. We could demonstrate mRNA overexpression of Wnt-1, -2, -9a, -9b, -10a, -10b and -16 in SSc skin. Wnt-1, -4 and -10b consistently showed strong expression in SSc skin when compared with healthy skin. On protein level, however, Wnt-4 was indistinguishable between SSc patients and healthy controls, whereas Wnt-1 and Wnt-10b protein levels were increased in SSc skin. The overexpression of Wnt-1 and Wnt-10b resulted in a prominent nuclear accumulation of β-catenin in fibroblasts. Finally, increased mRNA levels of the target gene axin-2 confirmed the activation of canonical Wnt signalling. In dEx3 β-catenin (wt/ex) mice, we addressed the consequences of enhanced Wnt signalling and increased accumulation of β-catenin in SSc. We selectively targeted β-catenin in fibroblasts. Cre-activated dEx3 β-catenin (wt/fl) × Col1a2; Cre-ER mice showed massive and spontaneous dermal thickening even 2 weeks after Cre activation. Eight weeks after Cre-activation, skin thickening cumulated at 102.6% (P < 0.001). In line with the dermal thickening, hydroxyproline content and myofibroblast counts showed strong increases. To test the therapeutic potential of targeting β-catenin/Wnt signaling, we created Ctnnb1(fl/fl) x Col1a2;Cre-ER mice to specifically delete β-catenin in fibroblasts. After Cre activation and β-catenin deletion in fibroblasts, mice were challenged with bleomycin subcutaneously for 4 weeks. We found that Cre-activated Ctnnb1(fl/fl) × Col1a2; Cre-ER mice were protected from bleomycin-induced dermal with a reduction of skin thickening by 71% (P < 0.05). Conclusions. We demonstrated a prominent activation of canonical Wnt signalling in SSc with nuclear accumulation of β-catenin in fibroblasts and activation of the target gene axin-2. Our results showed that fibroblast-specific stabilization of β-catenin resulted in enhanced collagen release, whereas deletion of β-catenin potently reduced collagen production. Together, our findings highlight a key role of β-catenin in fibroblast activation and fibrosis. Thus, β-catenin may be promising molecular target for anti-fibrotic therapie
Measurement of lepton universality parameters in and decays
A simultaneous analysis of the and decays is performed to test muon-electron universality in
two ranges of the square of the dilepton invariant mass, . The measurement
uses a sample of beauty meson decays produced in proton-proton collisions
collected with the LHCb detector between 2011 and 2018, corresponding to an
integrated luminosity of . A sequence of multivariate
selections and strict particle identification requirements produce a higher
signal purity and a better statistical sensitivity per unit luminosity than
previous LHCb lepton universality tests using the same decay modes. Residual
backgrounds due to misidentified hadronic decays are studied using data and
included in the fit model. Each of the four lepton universality measurements
reported is either the first in the given interval or supersedes previous
LHCb measurements. The results are compatible with the predictions of the
Standard Model.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-045.html (LHCb
public pages
Observation of Cabibbo-suppressed two-body hadronic decays and precision mass measurement of the baryon
The first observation of the singly Cabibbo-suppressed
and decays
is reported, using proton-proton collision data at a centre-of-mass energy of
, corresponding to an integrated luminosity of , collected with the LHCb detector between 2016 and 2018. The
branching fraction ratios are measured to be
,
. In addition, using the
decay channel, the baryon
mass is measured to be , improving the
precision of the previous world average by a factor of four.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-011.html (LHCb
public pages
Measurement of boson production cross-section in collisions at TeV
The first measurement of the boson production cross-section at
centre-of-mass energy TeV in the forward region is reported,
using collision data collected by the LHCb experiment in year 2017,
corresponding to an integrated luminosity of . The
production cross-section is measured for final-state muons in the
pseudorapidity range . The integrated cross-section is determined to be for the di-muon invariant
mass in the range . This result and the
differential cross-section results are in good agreement with theoretical
predictions at next-to-next-to-leading order in the strong coupling.
Based on a previous LHCb measurement of the boson production
cross-section in Pb collisions at TeV, the nuclear
modification factor is measured for the first time at this
energy. The measured values are in the forward region () and
in the backward region
(), where represents the muon rapidity in
the centre-of-mass frame.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2023-010.html (LHCb
public pages
Study of charmonium decays to in the channels
A study of the and decays
is performed using proton-proton collisions at center-of-mass energies of 7, 8
and 13 TeV at the LHCb experiment. The invariant mass spectra from
both decay modes reveal a rich content of charmonium resonances. New precise
measurements of the and resonance parameters are
performed and branching fraction measurements are obtained for decays to
, , and resonances. In particular, the
first observation and branching fraction measurement of is reported as well as first measurements of the
and branching fractions. Dalitz plot analyses of
and decays are performed. A
new measurement of the amplitude and phase of the -wave as functions
of the mass is performed, together with measurements of the
, and parameters. Finally, the branching
fractions of decays to resonances are also measured.Comment: All figures and tables, along with any supplementary material and
additional information, are available at
https://cern.ch/lhcbproject/Publications/p/LHCb-PAPER-2022-051.html (LHCb
public pages
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