Multimodal Freight Transport (MFT) has been introduced as a solution for reducing the external costs of freight transport while achieving cost improvements. Despite the MFT benefits, its share has been low in practice, and transport by trucks remains the most preferred transport mode. A few works have recently investigated this issue by discussing various barriers to MFT. However, little conceptual work comprehensively examines the barriers that organizations may face during MFT applications. To address this gap, this paper has reviewed 104 studies and identified 31 barriers and possible strategies for overcoming them. To clarify the nature of these barriers, we developed a conceptual barrier framework that positions the identified barriers within the overall MFT chain. This framework categorizes the barriers into six categories: MFT terminal, MFT network, management, regulations and subsidies, delivery characteristics, and interoperability. The findings provide decision-makers and practitioners with theoretical and practical insights into the barriers to transition toward MFT and will assist them in implementing MFT successfully.

Solar air heating (SAH) is a low-cost method for air heating using solar energy. An energy and exergy performance is performed experimentally on new designed tubular SAH having tubular absorber of adjacent tubes forming flat pack. Each tube of the absorber contains three adjacent internal tubes forming nabla shape (∇). The nabla tubular SAH (∇TSAH) performance is studied compared to ordinary tubular SAH (OTSAH) having tubular absorber only for single pass (SP) and double pass (DP) flow conditions and different mass flow rates of air (MFRA). The study is investigated under upper Egypt hot climate conditions and 0.018–0.081 kg/s MFRA. The results demonstrate that ∇TSAH has higher outlet air temperature, energy gain, higher energy, exergy, and thermohydraulic efficiencies, and lower top losses than the OTSAH. The new design boosts the exit air temperature by about 13.5 and 5 °C for SP and DP …

In this article, the spectrum trading problem between primary users and secondary networks is
investigated. The secondary network requests multiple channels with the targeted availability to satisfy its
users' demands. Due to the uncertainty about the channels availability, stochastic optimization techniques
are adopted to nd the optimal set of channels for each secondary network for the lowest cost. Two different
constraints on the secondary demand are dened. The rst one is when the throughput has to be fully satised
for a certain percentage of time, and the second one is when the expected value of the throughput has
to exceed a certain percentage of the requested one. Also, the possibility for channel subleasing among
the secondary networks is investigated to reduce the demand shortage. The results show that demanding
simultaneous channels increases the cost as it reaches up to 20% higher than if the same resources were
requested individually. Also, channels subleasing reduces the demand shortage probability and increases
the achieved throughput, especially at low value of requested demand. In this case, the demand satisfaction
probability increases by around 30% while the achieved throughput increases up to 40% compared to the
scenario where channels subleasing is not allowed.