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The little snowplow
On the Mighty Mountain Road Crew, the trucks come in one size: BIG. That is, until the little snowplow joins the crew. None of the other trucks think that the little snowplow can handle the big storms, but he knows that he can do it--and just to be sure, he trains hard, pushing loads of gravel, pulling blocks of concrete, and doing plow lifts to get ready. But when a blizzard arrives, will the little snowplow's training be enough to clear the streets and handle unexpected trouble?
Book
Optimization of Snowplow Routes for Real-World Conditions
During the winter season, snowplowing has a significant effect on road users as it is critical to winter road maintenance and operations. The main goal of this study is to generate optimal routes for snowplowing trucks for efficient road maintenance. In addition to the conventional problem of reducing travel time and distance, this study also incorporates actual operational constraints, such as minimum maintenance standards and driver safety, to improve the overall efficiency of operations. To achieve the objectives, we first implemented the Chinese Postman Problem (CPP) to create Euler circuits from the initial routes and then identified the shortest paths by applying Dijkstra’s algorithm. Then, the Tabu search algorithm was chosen as a metaheuristic algorithm for the optimization process that finds near-optimal solutions by considering operational constraints for snowplow routes. Unsafe turning conditions and minimum maintenance standards were taken into account in the objective function defined for the optimization process. In simulations, the route obtained by our approach was compared to one with the application of CPP only in terms of travel distance, time, turning conditions, and road maintenance priority.
Journal Article
Hydrodynamic splitting of laser-induced plasma plumes: two-dimensional kinetic simulations
The two-dimensional axisymmetric plasma plume expansion induced by irradiation of a copper target in argon background gas with a nanosecond laser pulse is studied based on a combined computational model. The model includes a thermal model of the irradiated target, the Hertz–Knudsen model of material removal, and a kinetic model of the multicomponent plasma plume. The kinetic model is implemented in the form of the direct simulation Monte Carlo method combined with a special approach to simulate equilibrium ionization in the plume, absorption of laser radiation through photoionization and inverse bremsstrahlung, as well as emission of bremsstrahlung radiation in free–free transitions. The simulations show that, at moderate peak laser fluence and background gas pressure, the bimodal distributions of radiation emission intensity appear due to the snow–plow effect that induces formation of a high-density and high-temperature zone at the plume edge between the secondary and primary shock waves. As a result, the transient splitting of the plume into the slow component, which corresponds to the plume core, and fast component, which corresponds to the plume edge, is observed. With increasing expansion time, the slow component disappears due to a relatively fast drop of density and temperature in the plume core. The simulations also show that an increase in the laser spot size is favorable for observing splitting in laser-induced plumes due to the snow–plow effect.
Journal Article
Prospective Quasi-Experimental Study of Postoperative Pain Following Class II Composite Restorations Using the Snow-Plow and Resin-Coating Techniques
Background/Objectives: Postoperative sensitivity remains a common challenge following direct composite restorations, especially in Class II cavities with deep proximal boxes. The snow-plow and resin-coating techniques have been proposed to improve marginal adaptation and reduce postoperative discomfort; however, comparative clinical data remain limited. This prospective, split-mouth, quasi-experimental study aimed to compare postoperative pain associated with Class II restorations placed using either the snow-plow or resin-coating technique. Methods: This prospective, split-mouth study followed 83 adult patients (aged 18–45 years) who received bilateral Class II composite restorations for one week. The study received ethical approval. Each participant received one restoration using the snow-plow technique and another using the resin-coating approach. Pain intensity was evaluated using a 10-point visual analog scale (VAS) at baseline, 24-h, 72-h, and 1-week postoperatively. Analyses included Wilcoxon signed-rank, Friedman, Chi-square, McNemar, and two-way repeated-measures ANOVA tests. Results: Pain intensity peaked at 24-h for both techniques and declined significantly by 72-h and 1 week (p < 0.001). The snow-plow technique showed slightly lower mean pain scores at 24 and 72 h (p = 0.026 and p = 0.004, respectively), though categorical analyses revealed no significant difference in pain-free or minimal-pain proportions at any interval (p > 0.05). Both techniques showed significant within-group reductions in pain over time (p < 0.001). Conclusions: Both restorative approaches demonstrated similar postoperative pain trajectories, with substantial improvement by one week. While minor differences in early mean pain intensity were observed, these were not clinically significant. The findings suggest that either technique can be effectively employed to achieve satisfactory postoperative comfort when modern adhesive protocols are applied. Clinicians can therefore select either technique based on preference and clinical circumstances, with the expectation of comparable short-term postoperative comfort outcomes.
Journal Article
Study on the Restoration of Class II Carious Cavities by Virtual Methods: Simulation of Mechanical Behavior
The restoration of class II cavities is predominantly carried out with composite materials. Due to the high failure rate in restoring this type of cavity, composite materials with much-improved properties and new application techniques have been promoted. The study aimed to analyze the mechanical behavior of several topical composite materials (nanocomposites, nanohybrids and ormocer) using different application techniques. In a lower second molar, a class II occlusal cavity was prepared. As filling materials, we used the following combinations: Admira Fusion and Admira Fusion Flow, Grandio and Grandio Flow, Filtek Supreme XT and Filtek Supreme Flow. These were applied using a snow plow, injection molded and Bichacho techniques. Three-dimensional scanning of the molar with the prepared cavity was performed, and then scanning of each layer of added composite material was performed, obtaining three-dimensional models. The virtual molar models were analyzed with software specific to the finite element analysis method, where their physical-mechanical properties were entered and assigned to the components of the virtual molar. Simulations at high forces specific to bruxism were then carried out and analyzed, and compared. The values of displacements and strain, for all six analyzed situations, are relatively small (range from 5.25 × 10−6–3.21 × 10−5 for displacement, 6.22 × 10−3–4.34 × 10−3 for strain), which validates all three methods and the materials used. As far as the stress values are concerned, they are similar for all methods (250–300 MPa), except for the snow plow and injection-molded techniques using Grandio and Grandio Flow composites, where the maximum von Mises stress value was more than double (approximately 700 MPa). When using the combination of Grandio and Grandio Flow materials, the 1 mm thickness of the fluid composite layer was found to have a major influence on occlusal forces damping as opposed to 0.5 mm. Therefore, the Bichacho technique is indicated at the expense of the snow plow and injection-molded techniques. The composite materials used by us in this study are state-of-the-art, with clear indications for restoring cavities resulting from the treatment of carious lesions. However, their association and application technique in the case of Class II cavities is of clinical importance for resistance to masticatory forces.
Journal Article
Investigation on aerodynamic noise reduction for snow-plough of high-speed train
A set of acoustic optimization design methods is established by combining the flow field deterioration theory and the acoustic analogy theory, and applied to the acoustic optimization design of high-speed train snow-plough. The results show that the streamline bodies of the head/tail car are the most important sound sources, respectively, accounting for 23.7% and 33.7% of the total sound energy. Compared with the streamline body of tail head, the streamline body of head car is more biased towards high frequency for the sound source energy. The A-weighted radiated noise of the train body is characterized by broadband sound (mainly in the range of 1–4 kHz) and peak features (especially at 2 kHz). The snow-plough with the maximum expansion length can mitigate the strong peak effect of the sound at 2 kHz, reduce the total sound energy, and show the best acoustic radiation performance in the four schemes. The numerical computation model was checked by the wind tunnel test results.
Journal Article
Pilot Testing a Naturalistic Driving Study to Investigate Winter Maintenance Operator Fatigue during Winter Emergencies
Although numerous research studies have investigated the effects of fatigue in commercial motor vehicle drivers, research with winter maintenance (WM) drivers is sparse. This study pilot-tested the feasibility of evaluating WM operator fatigue during winter emergencies using naturalistic driving data. Four WM operators participated in the study and drove two instrumented snow plows for three consecutive winter months. The operators also wore an actigraph device used to measure sleep quantity. As this was a pilot study, the results were limited and only provided an estimation of what may be found in a large-scale naturalistic driving study with WM operators. Results showed the majority of safety-critical events (SCEs) occurred during the night, and approximately half of the SCEs occurred when participants were between 5 and 8 h into their shifts. Fatigue was identified as the critical reason in 33% of the SCEs, and drivers were found to average less sleep during winter emergencies versus winter non-emergencies. However, one participant accounted for all fatigue-related SCEs. Although data were limited to two instrumented trucks and four drivers, results support the approach of using naturalistic driving data to assess fatigue in WM operators. Future on-road research is needed to understand the relationship between fatigue and crash risk in WM operators.
Journal Article