Detour Strategy Research Articles

Robust multimodal hub network design for hazmat considering a detour strategy

Most traditional hub networks focus on ordinary cargo transportation and usually limit the number of transshipment occurrences to minimise costs. However, this limitation is not conducive to the transportation of hazmat, which often requires detours to avoid high risks. Therefore, this paper proposes a new multimodal network model considering a detour strategy and discusses the uncertainty in the network from the demand point of view. The method of robust optimisation is used to address the uncertainty in the proposed model, and the Lagrange relaxation algorithm and augmented ɛ-constraint method are used to transform and simplify the model. In addition, simulated data of hazmat transportation in the Yangtze River Delta urban agglomeration are used for a case study. The results show that under the consideration of uncertain demand, changes in the demand uncertainty degree and transit discount factor cause changes in the total cost and risk of the multimodal hub network, thus affecting the carrier’s location and route decisions; the new model can better control and mitigate risk, which is more suitable for hazmat transportation. This study provides a reference for multimodal transport carriers in hazmat transportation decision making.

Design Optimization of a HAZMAT Multimodal Hub-and-Spoke Network with Detour.

The growing transportation risk of hazardous materials (hazmat) is an important threat to public safety. As an efficient and reliable mode of transportation, the multimodal hub-and-spoke transport network helps to achieve economies of scale and reduce costs. Considering the dual goals of risk and cost management of hazmat transportation, a novel optimization model of a multimodal hub-and-spoke network with detour (MHSNWD) for hazmat on the strategic level is designed. It integrates the planning of hub location and route selection based on the risk quantification for different transportation modes. Additionally, a detour strategy is applied, which allows for more than two hub nodes to be selected to form an optimal path between any supply and demand nodes in a hub-and-spoke network. Then, the risk is taken as the main objective and the cost is converted into a budget constraint to solve the model by using CPLEX. Additionally, a numerical study is conducted based on a CAB dataset to find the influence of the number of hubs and budget constraints on the optimization results. In addition, a counterpart model of the multimodal hub-and-spoke network without detour (MHSNOD) is tested to validate the advantages of the proposed model of MHSNWD. The numerical experiment shows that an appropriate increase in the number of hubs and the cost budget can remarkably reduce network risk. Compared with MHSNOD, the optimal result of MHSNWD can achieve a marginal improvement in risk reduction. This work may provide an informative decision-making reference for planning a hazmat transportation network.

Le réel à l’épreuve de la fiction dans « Khalil » de Yasmina Khadra

<p class="Corps">In <em>Khalil</em>, Yasmina Khadra paints a realistic portrait of a terrorist. This novel written in 2018 and developed from a real fact, blurs the spaces of reality and fiction to reveal the apparently unavowable thoughts of a jihadist. It is this detour strategy that this article will seek to clarify. It will be a question of studying how Yasmina Khadra organizes a scrambling of these two worlds, the fictional space and the realistic space, located at the edge of each other, to make them interact, confront each other but also to question.</p>

Significantly Improved Recovery of Recombinant Sonchus Yellow Net Rhabdovirus by Expressing the Negative-Strand Genomic RNA

Generation of recombinant negative-stranded RNA viruses (NSVs) from plasmids involves in vivo reconstitution of biologically active nucleocapsids and faces a unique antisense problem where the negative-sense viral genomic RNAs can hybridize to viral messenger RNAs. To overcome this problem, a positive-sense RNA approach has been devised through expression of viral antigenomic (ag)RNA and core proteins for assembly of antigenomic nucleocapsids. Although this detour strategy works for many NSVs, the process is still inefficient. Using Sonchus yellow net rhabdovirus (SYNV) as a model; here, we develop a negative-sense genomic RNA-based approach that increased rescue efficiency by two orders of magnitude compared to the conventional agRNA approach. The system relied on suppression of double-stranded RNA induced antiviral responses by co-expression of plant viruses-encoded RNA silencing suppressors or animal viruses-encoded double-stranded RNA antagonists. With the improved approach, we were able to recover a highly attenuated SYNV mutant with a deletion in the matrix protein gene which otherwise could not be rescued via the agRNA approach. Reverse genetics analyses of the generated mutant virus provided insights into SYNV virion assembly and morphogenesis. This approach may potentially be applicable to other NSVs of plants or animals.

MF-HER: Marine Mammal-Friendly Based High Spectral-Efficient Routing for Underwater Acoustic Sensor Networks

In real ocean environments, artificial acoustic and natural acoustic systems are coexisted to share scarce spectrum resources. In this paper, we propose a marine mammals-friendly based high spectral-efficient routing (MF-HER) protocol to improve spectrum utilization and protect marine mammal communications in underwater acoustic sensor networks (UW-ASNs), which makes full use of the interlacing frequency bands that are shared by both marine mammals and UW-ASNs. In the proposed MF-HER protocol, the detour strategy is adopted to adaptively avoid the interference of acoustic radiation from sensor nodes to the acoustic communication habits of marine mammals. Meanwhile, the non-detour strategy is adopted if there is no marine mammal or the marine mammals do not use the same frequency bands for communication in the sea area, and thus the sensor nodes can fully utilize the frequency bands without interference from the marine mammals. Due to the diversity of acoustic frequency bands used by marine mammals, the reasonable design of a routing protocol can shorten the distance of forwarding path and optimize the performance of UW-ASNs while protecting marine mammals. Simulation results show that, as compared to the existing bio-friendly routing protocol of UW-ASNs, the proposed MF-HER protocol can effectively improve the energy consumption of the sensor nodes, bit error rate, and network throughput, while avoiding the communication masking effect among marine mammals.

A detour strategy for colloidally stable block-copolymer grafted MAPbBr3 quantum dots in water with long photoluminescence lifetime.

Perovskite quantum dots (PQDs) exhibit remarkable photoluminescence properties; however, their use in biological applications is hindered by their extreme sensitivity to water. We report a facile and general strategy for the preparation of aqueous colloidally stable polystyrene-b-poly(ethyl oxide) (PS-b-PEO) grafted MAPbBr3 QDs (MA = methylammonium): transferring the as-synthesized PQD@PS-b-PEO from toluene into water using precipitation in hexane as a critical intermediate step. When rehydrating the precipitate in water, the PQDs can be dispersed well individually or self-assembled into well-defined vesicular nanostructures with high photoluminescence quantum yields of up to 43%, high color purity (full width at half maximum down to 18 nm), and long average photoluminescence lifetimes up to 164 ns. The resulting PQD nanostructures in water also show excellent thermo- and photo-stability, low cytotoxicity, and bright potential for cell imaging. This work highlights the future prospects of using polymer-modified PQDs with desired physicochemical properties for biomedical applications.

Synthetic Access Toward Cycloastragenol Glycosides.

The first efficient synthetic approach toward four types of the cycloartane glycosides, the cycloastragenol 25-O; 3-O; 3,6-O-bis; and 3,25-O-bisglycoside, have been established, which featured the PPY-mediated, concentration-controlled acetylation and Au(I)-catalyzed Yu glycosylation. Through the synthetic investigation, the reactivity sequence of the four OHs in cycloastragenol was fixed for the first time and a detour strategy for the highly efficient removal of bulky pivaloyl protecting groups was discovered.

Sparse signal reconstruction via concave continuous piecewise linear programming

Compressed sensing (CS) is a new paradigm for acquiring sparse and compressible signals which can be approximated using much less information than their nominal dimension would suggest. In order to recover a signal from its compressive measurements, the conventional CS theory seeks the sparsest signal that agrees with the measurements via a great many algorithms, which usually solve merely an approximation of the l0 norm minimization. In this paper, CS has been considered from a new perspective. We equivalently transform the l0 norm minimization into a concave continuous piecewise linear programming based on the prior knowledge of sparsity, and propose a novel global optimization algorithm for it based on a sophisticated detour strategy and the γ valid cut theory. Numerical experiments demonstrate that our algorithm improves the best known number of measurements in the literature, relaxes the restrictions of the sensing matrix to some extent, and performs robustly in the noisy scenarios.

Decision Model for Justifying the Benefits of Detour Operation under Non-Recurrent Congestion

Non-recurrent traffic congestion due to incidents, highway construction zones, and special events has contributed up to 60% of the total freeway corridor delay in the United States. Under most scenarios, if proper diversion plans can be implemented in time, motorists can circumvent the congested segments and best use the available corridor capacity. Nevertheless, before the implementation of any detour strategy, traffic managers must ensure the resulting benefits, because implementing those advanced control strategies usually demand substantial amount of resources and manpower. This study, proposed in response to such needs, presents a detour decision methodology for urban freeway non-recurrent congestion management, based on the results of extensive simulation experiments and operational guidelines from highway agencies. The proposed model offers a reliable and effective tool for responsible traffic management personnel to make consistent detour decisions in response to a detected incident. Numerical results clearly indicate that a timely and well-justified detour operation can yield substantial benefits to both the driving population and the entire community.

Advanced Traffic Management System

Implementing a well-designed detour plan to minimize the impact of nonrecurrent congestion has long been adopted by responsible highway agencies, mainly on the basis of estimated incident duration or number of blocked lanes. Because an effective detour operation necessitates rigorous plans in advance and a vast amount of resources during implementation, a convincing justification for taking such actions becomes increasingly essential in practice, especially in view of diminishing resources for traffic management. This paper presents a multicriterion decision support system to assist traffic managers in effectively making such decisions in real-time operations by taking into account (a) associated costs and benefits from various perspectives, including the operational cost, and (b) the resultant benefits from reduced delay, fuel consumption, and emissions, as well as (c) the likelihood of incurring secondary incidents. The impact of potential driver compliance in response to the detour strategy and of the local traffic condition on the effectiveness of detour operations can be included in the decision process. The proposed system, with its embedded analytical hierarchy process structure and optimal corridor detour model, allows potential users to rank by priority all essential decision criteria (on the basis of either resource constraints or the demand of the general public) and to make the critical decision that can best manage any nonrecurrent congestion and maximize the total resultant socioeconomic benefits.

A Detour Strategy for the Test Ban Treaty

Arms control supporters are impatient with the Obama administration as it completes its third year in office. Neither the strength nor the pace of nuclear policy reform has been to their liking. In...