Rip currents are the strong narrow seaward current produced by waves breaking on the coast. Of the many types of rip currents, the present study investigates, experimentally and numerically, the rip current system produced by the wave reflection on a finite-length shore-normal structure (corresponding to groin, jetty and headland in a real-word environment) with strong wave reflection strength. The incident wave condition of an obliquely propagating monochromatic surface gravity wave is considered for the bottom topographies of planar and barred beaches without or with a rip channel. The corresponding laboratory experiment was conducted and used to validate the numerical model. A set of higher order Boussinesq equations is used to reproduce the experimental observation and produce the results for the related prototype cases, with the latter considering more factors which may influence the formation and evolution of rip current flow patterns. The resulting rip current system contains two parts: the node rips formed due to the presence of the longshore standing wave in the wave reflection field and the deflection rip formed due to the interaction between the incoming longshore current and the reflection wave field mentioned above. A new formation mechanism of the deflection rip has been proposed, i.e., the deflection rip is formed by the meeting and then deflection of the longshore current and lateral flow. The effects of different wave reflection strengths of the structure, wave incident angles and bathymetric conditions on the pattern and flow volume of the deflection rip are also studied.

In order to address the dynamic changes in vessel preferences for berth lines caused by the deployment of shore-based power equipment in major ports and the collaborative scheduling problem of berthing and towing assistance, this paper quantifies the environmental costs of pollutants from the main engines of tugs and auxiliary engines of container ships using an environmental tax. Additionally, considering the economic costs such as vessel delay and shore power cable connection, a two-layer mixed-integer linear programming model is constructed using the task sequence mapping method. This model integrates the allocation of continuous berths at container terminals with coordinated towing scheduling for shore power selection. A solution approach is designed by combining the commercial solver (CPLEX) and the immune particle swarm optimization algorithm (IAPSO). The proposed scheme is validated using the example of the Nansha Phase IV Terminal at the Port of Guangzhou. The results show that compared to the traditional first-come-first-served and adjacent scheduling schemes, the collaborative scheduling scheme proposed in this paper reduces the total cost by 21.73%. By effectively utilizing berth resources and shore power equipment while densely arranging collaborative tasks and appropriately increasing the number of tugs, the port can convert the economic cost of leasing a small number of tugs (increased by 10.63%) into environmental benefits (decreased by 33.88%). This approach provides a reference for addressing nearshore pollution emissions in ports.

To analyze the impacts of groins, sandbars, and channels on the three-dimensional features of rip currents, we conducted experimental investigations on the vertical distribution of rip currents under intersecting waves along barred beaches with channels. This study employed ADV flow velocity measurements at two distinct locations: within channel and on a sandbar. The results indicate that in nodal sections within channel and on a sandbar, the rip head region manifests surface flow characteristics, characterized by high velocities near water surface. In a rip neck location, the vertical distribution of rip currents on a sandbar exhibits greater variability, whereas within channel, the distribution is more homogeneous. The vertical distribution of rip currents in nodal sections within channel aligns with the logarithmic distribution law. The vertical distributions of the alongshore velocity of rip currents display a consistent pattern of higher at the top and lower at the bottom. However, this pattern varies slightly depending on the wave period. The presence of groins influences the fluctuation characteristics of the alongshore velocity of rip currents by regulating the nearshore circulation system. This results in the alongshore velocity of rip currents in channel pointing towards the groin. In contrast, the alongshore velocity of rip currents on sandbar, situated farther away from groin, exerts a weaker effect on the alongshore velocity of a rip current.

Double-line ship mooring (DLSM) can allow an outer feeder vessel to be handled alongside an inner mainline vessel and thereby enable direct ship-to-ship container transshipment. The aim of this study is to determine whether, and under what modeled conditions, a static one-to-one DLSM arrangement can improve berth and quay-crane planning while enabling direct transfer. A normative formulation represents berth sharing, vessel-length compatibility, temporal containment, terminal-wide crane capacity, and the lower productivity of a cross-over quay crane. The executable framework addresses a restricted decision space: particle swarm optimization (PSO) searches berth assignments, deterministic rules generate quay-crane counts and DLSM pairs, and a constructive scheduler produces and evaluates service times. Performance is assessed through a two-by-two FCFS/PSO and SLSM/DLSM ablation on 45 synthetic instances, supplemented by 20 independent runs of each PSO scheme on nine prospectively selected representative instances. PSO-DLSM reduced the composite objective by 49.27% relative to PSO-SLSM in the repeated-run analysis (two-sided paired t-test, Holm-adjusted p < 0.001; Cohen’s dz = 2.27), whereas PSO-SLSM did not significantly outperform FCFS-SLSM. Sensitivity analyses further show that DLSM performance is conditional on cross-over handling efficiency, the penalty assigned to indirect transshipment, and binding quay-crane capacity. The evidence therefore attributes the observed improvement to the complementarity between berth search and DLSM-enabled direct transfer rather than to PSO alone. An independent-feeder-arrival stress test showed that the benefit can disappear when compatible overlaps are scarce. The framework therefore supports conditional planning-level screening, not a general performance guarantee.