Study on the Availability Opening Size of Throttle and Affection to the Velocity Characteristic of Shock Absorber

Based on the solution of the governing differential equation for deformation of throttle slice while satisfying required boundary conditions, the coefficient （Gr） and an analytical formula for computing the deformation of throttle slice is presented through equivalency transformation, which is a concise, accurate and practical method for throttle slice design and characteristic analysis. Researched the deformation at any radius, compared with ANSYS FEA software by the simulation analysis, the availability opening size of throttle that was defined by the deformation at the valve mouth radius is studied. The affection of valve mouth radius to the damper characteristic is analyzed. Tests are made for the damper characteristic, compared with simulation results, it is shown that Gr method is an accurate computation method for computing the deformation of throttle slice at valve mouth radius, suitihle to use in the damper design, analysis, and verification. The deformation at mouth radius could not be replaced with the outside radius.

Effect of Opening Size on the Development of Ventilation-limited Fire

There are many factors,that affect the development of indoor fire,such as the size of the fire source,the opening or space of the room,and the nature of the combustible materials.Among them,the space of the room,has a significant impact on the development of a ventilation-limited fire.In this paper,the Fire Dynamics Simulator(FDS)software is used to analyze,the risk of fire initiation in the restricted ventilated compartment,when the size of vertical ventilation space is different.Through,a combination of experimental design,numerical simulation,and theoretical analysis,the changes in the level of carbon monoxide,visibility,temperature,Heat Release Rate(HRR)and,the smoke exhaust efficiency of natural smoke at different opening sizes are observed.It is observed that,when the ratio of inlet and outlet area reaches 2:1,the natural smoke exhaust effect is the best,however,the increasing in the opening size has little significance on the smoke exhaust effect.The research on the influence of smoke outlet size,will helps in the development of the law regarding fire prevention,smoke exhaust design,and fire rescue work of a building.

Effect of fence opening configurations on dune development

Fences have been widely used in coastal protection engineering for their low cost,simple deployment,and easy integration with ecosystems.The effects of fence porosity and height on dune development have been investigated while not much attention has been paid to the effects of fence opening configurations,such as opening size and geometry,and porosity distributions.In this study,we deployed eight fences with same height and similar porosity,but different opening configurations on a sandy beach in Pingtan,Fujian Province.Results indicate that there is a similar two-dune-one-trough pattern for all fences at the beginning of dune development,and opening size,orientation,and geometry,and porosity distribution control the leeward dune peak locations.Fences with small openings and non-uniform porosity have high trapping efficiency,and upper denser porosity may be the optimal design as these fences have the highest trapping efficiency and capacity.The conclusions from this study can provide guidance on practical fence design.

Impact pressure of debris flow on beam dam

The use of open-type check dams in mountainous areas has become common practice in order to mitigate the effects of debris flow and extend the service life of engineering structures.The beam dam,a common debris flow control system,has received less attention in research on the impact process of debris flow and check dams compared to solid check dams.Additionally,the estimation of impact pressure in debris flow primarily considers debris flow characteristics,without taking into account the influence of geometric characteristics of the transmission structure.To better understand the impact process of debris flow on beam dams,a series of small-scale debris flow impact tests were conducted in a model flume.Key parameters,including velocity,depth,and impact pressure,were measured.The results show that the maximum impact pressure of debris flow is affected by both the characteristics of the debris flow and the relative opening size of the beam dam.Due to flow and edge occlusion in the middle of the beam dam,the discharge of debris flow is enhanced,resulting in a longer impact process and higher maximum impact pressure.Based on these findings,a calculation model of the maximum impact pressure of debris flow at the midpoint of the middle beam is proposed,which can be used to estimate the impact of debris flow on the discharge part of the beam dam.

Exploring Factors Influencing Species Natural Regeneration Response Following Harvesting in the Acadian Forests of New Brunswick

In the Acadian Forest Region of northeastern North America, forest managers are under increasing public pressure to restore the forest to a more historic, natural condition by reducing in clearcutting and promoting partial-cut treatments that more closely emulate historic, local natural disturbance regimes. However, although numerous studies on the effects of partial-cutting on forest regeneration response have been conducted in surrounding temperate and boreal forest ecosystems, there are few studies that directly explore responses to various forms of harvesting within the Acadian Forest ecosystem, with its unique mixture of northern hardwoods and boreal forest species. Here, we conducted one of the first retrospective studies on forest regeneration following a variety of harvesting methods in the Acadian Forest using univariate and multivariate regression trees to assess regeneration response in 50 naturally-regenerating, harvested forest sites in New Brunswick, Canada. Our study shows that regeneration was highly influenced by harvest type, overstory composition, and environmental conditions as reflected by ecoregion classification. Canopy opening size (as controlled by harvest method) significantly influenced the dominance of regenerating species. The presence of conspecific overstory trees increased the likelihood of their regeneration following disturbance, supporting the direct-regeneration hypothesis, especially for species with limited seed dispersal (e.g., sugar maple (Acer saccharum Marsh.) and American beech (Fagus grandifolia Ehrh.). Despite reported problems elsewhere in eastern North America, neither American beech nor balsam fir (Abies balsamea (L.) Mill.) constituted significant competition for the desired species on a broad scale, but the presence of beech was a significant deterrent for yellow birch (Betula alleghaniensis Britt.).

FILTER PRESSING BEHAVIOUR OF ALUMINA DISPERSIONS

Studies of pressure-volume curves have shown that the filter pressing behaviours depend on pH values of the alumina dispersion. Densimetry and porosimetry of the filter cakes have revealed that higher density, smaller mode pore size and lower specific volume of total pores can be achieved by controlling electrostabilization. (Author abstract) 9 Refs.