A Combination of Spatial Domain Filters to Detect Surface Ocean Current from Multi-Sensor Remote Sensing Data

This research investigates the applicability of combining spatial filter’s algorithm to extract surface ocean current. Accordingly, the raster filters were tested on 80–13,505 daily images to detect Kuroshio Current (KC) on weekly, seasonal, and climatological scales. The selected raster filters are convolution, Laplacian, north gradient, sharpening, min/max, histogram equalization, standard deviation, and natural break. In addition, conventional data set of sea surface currents, sea surface temperature (SST), sea surface height (SSH), and non-conventional data such as total heat flux, surface density (SSD), and salinity (SSS) were employed. Moreover, controversial data on ocean color are included because very few studies revealed that chlorophyll-α is a proxy to SST in the summer to extract KC. Interestingly, the performance of filters is uniform and thriving for seasonal and on a climatological scale only by combining the algorithms. In contrast, the typical scenario of identifying Kuroshio signatures using an individual filter and by designating a value spectrum is inapplicable for specific seasons and data set. Furthermore, the KC’s centerlines computed from SST, SSH, total heat flux, SSS, SSD, and chlorophyll-α correlate with sea surface currents. Deviations are observed in the various segments of Kuroshio’s centerline extracted from heat flux, chlorophyll-α, and SSS flowing across Tokara Strait from northeast Taiwan to the south of Japan.

Heat Fluxes Localization and Abnormal Size Effect Induced by Multi-Body Vibration in Complex Networks

Heat conduction in real physical networks such as nanotube/nanowire networks has been attracting more and more attention, but its theoretical understanding is far behind. To open a way to this problem, we present a multi-body vibration model of heat conduction to study how heat is conducted in complex networks, where nodes’degrees satisfy a random distribution and links consist of 1D atom chains with nonlinear springs. Based on this model, we find two interesting phenomenons: (1) The main heat fluxes of network are always localized in a skeleton subnetwork, which may have potential applications in thermal management and thermal concentrators, etc; (2) There exists an abnormal size effect of heat conduction in complex networks, i.e. the total heat flux of network will be enlarged with the increase of atoms on links, which is in contrast to the previous result on a 1D chain. Furthermore, we introduce a transmission diagram to characterize the skeleton of localized heat fluxes and then discover a phase transition of total heat flux in the process of removing links, implying that the control of heat flux can be effective only when the change of network topology is focused on the links within the skeleton. A brief theory is introduced to explain the abnormal size effect.

Steady State Thermal Effect on Static Characteristic of Copper Roller Shaft

The static analysis of a copper roller shaft is performed. The copper roller shaft consists of bushing, pen roll and roller. All of those components g4bconsist of different materials. Thermal steady state and statical analysis is performed in order to investigate the thermal effect of high temperature copper slab on the roller shaft. The copper slab temperature is 1200 OC. Based on this work obtained that the maximum total deformation is 0.0050523 m, maximum equivalent stress is 41600 MPa, maximum life cycle is 1011, total heat flux maximum is 879910 W/m2 and the maximum damage occur in the pen roll component.

Performance optimization of thin fire blankets by varying their radiative properties

In using thin fire blankets to protect structures in wildfires, heat rejections by radiation (reflection and emission) are essential for good performance. By varying the radiative properties of the front and back surfaces of the blankets, this article offers an optimization study of several scenarios of incident heat flux including pure convection, pure radiation, and combinations of the two. Two types of blanket heat-blocking efficiencies are studied in the optimization scheme. An overall efficiency is defined as the amount of incident heat blocked to the total amount of incident heat in specified wildfire scenarios. An instantaneous heat-blocking efficiency is defined as the instantaneous heat flux blocked to the instantaneous incident total heat flux which provides good understanding of the physics of heat-blocking mechanisms of fire blanket under quasi-steady conditions. In addition to maximizing these heat-blocking efficiencies, there are other optimization objectives, including the minimization of the blanket backside temperature. A genetic algorithm is used for the multi-objective optimization schemes. For the transient heat incidence, the optimization for the entire time sequence is performed with the possibility of a change of blanket radiative properties during the fire sequence, accounting for changes to the fire-facing surface caused by the incident heat.

A large-eddy simulation study of deep-convection initiation through the collision of two sea-breeze fronts

Deep convection plays important roles in producing severe weather and regulating the large-scale circulation. However, deep-convection initiation (DCI), which determines when and where deep convection develops, has not yet been fully understood. Here, large-eddy simulations are performed to investigate the detailed processes of DCI, which occurs through the collision of two sea-breeze fronts developing over a peninsula. In the simulation with a maximum total heat flux over land of 700 or 500 W m−2, DCI is accomplished through the development of three generations of convection. The first generation of convection is randomly produced along the colliding sea-breeze fronts. The second generation of convection only develops in regions where no strong downdrafts are produced by the first generation of convection and is also mainly produced through the collision of the sea-breeze fronts. The third generation of convection mainly develops from the intersection points of the cold pools produced by the second generation of convection and is produced through the collision between the gust fronts and the sea-breeze fronts. Decreasing the maximum total heat flux from 700 to 500 W m−2 weakens each generation of convection. Further decreasing the maximum total heat flux to 300 W m−2 leads to only one generation of shallow convection.

A large-eddy simulation study of deep-convection initiation through the collision of two sea-breeze fronts

Large-eddy simulations are performed to investigate the process of deep-convection initiation (DCI) over a peninsula. In each simulation, two sea-breeze circulations develop over the two coasts. The two sea-breeze fronts move inland and collide, producing strong instability and strong updrafts near the centerline of the domain, and consequently leading to DCI. In the simulation with a maximum total heat flux over land of 700 or 500 W m−2, DCI is accomplished through the development of three generations of convection. The first generation of convection is randomly produced through the collision of the sea-breeze fronts. The second generation of convection is produced mainly through the collision of the sea-breeze fronts, but only develops in regions where no strong downdrafts are produced by the first generation of convection. The third generation of convection mainly develops from the intersection points of the cold pools produced by the second generation of convection, and is produced through the collision between gust fronts and sea-breeze fronts. As the maximum total heat flux decreases from 700 to 500 W m−2, both the height and strength of the sea breezes are reduced, inhibiting the forcing of the first two generations of convection. These two generations of convection therefore become weaker. The weaker second generation of convection produces shallower cold pools, reducing the forcing of the third generation, and consequently weakening the third generation of convection. As the maximum total heat flux further decreases to 300 W m−2, only one generation of shallow convection is produced.

Finding the optimal compressor impeller material to improve the efficiency of the turbocharging system

Vehicles powered by diesel engines are equipped with superchargers in order to improve the ef-ficiency of vehicles. The efficiency of the turbochargers themselves partly depends on the optimum performance of their impellers, which in turn is achieved by choosing the right impeller materials. An important property of the material of the turbine wheel is heat resistance to the incoming exhaust gases, and for the compressor wheel it is the resistance to the pressure of the air simultaneously supplied to it and forced by it. In this paper, the issue of increasing the efficiency of the turbocharging system is considered in the context of comparing three materials (nickel and titanium alloys, structural steel), which are proposed for the manufacture of a compressor impeller by designing its model using computer software products. The measurements of real turbocharging elements and their characteristics are transferred to CREO, where the required dimensions are calculated and other necessary calculations are carried out, which are then imported into ANSYS for the purpose of subsequent research, in-cluding thermal and structural analyzes. Comparison of the analysis results allows us to conclude that the nickel alloy is superior to other materials under consideration in terms of its minimum sus-ceptibility to deformation and obtaining the lowest total heat flux in the compressor impeller, and to recommend this material for use in turbocharging or for its subsequent comparison with previously not considered materials, which, as suggested in the study, to some extent can contribute to an in-crease in the efficiency of the vehicle.

Numerical Simulation of Thawing Process in Frozen Soil

Permafrost has been thawing faster due to climate change which would release greenhouse gases, change the hydrological regimes, affect buildings above, and so on. It is necessary to study the thawing process of frozen soil. A water-heat coupling model for frozen soil thawing is established on Darcy’s law and Heat Transfer in Porous Media interfaces in Comsol Multiphysics 5.5. Three curves of total liquid water volume, minimum temperature, and total heat flux in the thawing process are obtained from a numerical simulation. The distributions of liquid water, temperature, and pressure based on time are simulated too. The liquid water distribution is consistent with the total liquid water volume curve. The temperature distribution is confirmed by the minimum temperature and total heat flux curve. The pressure distribution represents ice in the frozen soil that generates negative pressure during the melting process. The numerical simulation research in this article deepens the understanding of the internal evolution in the process of frozen soil thawing and has a certain reference value for subsequent experimental research and related applications.