Travel distance, characteristic

Bennett DH, Mckone TE, Matthies M, Kastenberg WE (1998) General formulation of characteristic travel distance for semivolative organic chemicals in a multimedia environment. Environ Sci Technol 32 4023 -030... 

Characteristic travel distance Environmental bioaccumulation potential Electron-capture negative ion mass spectrometry Estimation programs interface (EPI) suite European... 

POP Overall persistence CTD Characteristic travel distance TE Transfer efficiency... 

Fig. 1 Results for characteristic travel distance (CTD) and Transfer efficiency (TE) for 20 SCCP-MCCP-LCCP homologs in Table 2 are compared with reference compounds (a-HCH, aldrin, atrazine, biphenyl, CCI4, HCB, p-cresol), PCB congeners (CB 28, 101, 180), and PCB homologs (Cli to Clio). The curved line is the volatility line representing a physical limit on transport potential in the atmosphere defined by a hypothetical substance that partitions entirely into air [31]...

To better quantify the mobility of substances, indicators that can be calculated from the model results have been developed. Indicators for long-range transport potential are the spatial range [26,27], the characteristic travel distance (CTD) [33], the Great Lakes Transport Efficiency (GLTE) [34], and the Arctic contamination potential [35]. In the following two sections, we describe how such indicators have been adapted for transformation products. 

Characteristic travel distance (CTD) The distance (km) at which the concentration of a substance has decreased to 37% of the original concentration, assuming that the substance is transported by a constant flow of water (ocean speed 0.02 m/s) or air (4 m/s). The benchmark value, 5,097 km, is based on the model results for the reference chemical PCB-28. 

Substance Overall Persistence (days) Characteristic Travel Distance (km) Transport Efficiency (%)... 

As described above, the magnitude of Knudsen number, Kn, or inverse Knudsen number, D, is of great significance for gas lubrication. From the definition of Kn in Eq (2), the local Knudsen number depends on the local mean free path of gas molecules,, and the local characteristic length, L, which is usually taken as the local gap width, h, in analysis of gas lubrication problems. From basic kinetic theory we know that the mean free path represents the average travel distance of a particle between two successive collisions, and if the gas is assumed to be consisted of hard sphere particles, the mean free path can be expressed as... 

A high acid type contains more than 16% acid monomer (10). High acid ionomer types have been widely described in the production of golf balls. They are used in multi-piece balls that exhibit an enhanced travel distance while maintaining the playability and durability characteristics necessary for repetitive play (11). 

A characteristic of the CDE travel time distribution is that the variance of the travel times grows linearly with travel distance z. This is equivalent to the particle location distribution, which grows linearly with time for a Brownian motion process. As such, it is essential in the derivation of (12) that the hydrodynamic dispersion can be described as a diffusion process, i.e. on average, all solute particles are subjected to the same forces and the transport time is sufficiently large so that the incremental microscopic particle displacements are no longer statistically correlated. As a corollary, the CDE process cannot be valid for small soil volumes where the travel times are too small as compared to the mixing time, or to describe transport close to interfaces. 

The characteristics of the routes of egress to an exit are also important, especially in as critical a facility as a laboratory building. Care should be taken, just as within the laboratory, for the distances to be as short and direct as practicable. The location of hazardous areas should be chosen to eliminate or minimize the probability of the direction of travel on a primary or secondary evacuation route being toward a likely hazard during an emergency. The normally allowed maximum travel distances for the... 

Spatial modeling of rockfalls hazard was conducted using RockFall Analyst (Fan et al., 2007), a three-dimensional GIS extension, to determine the characteristics of rock blocks landing on or crossing over the highway in terms of traveling distance, velocity and volume. The modeling procedure is... 

The building design will determine the travel distances to reach a place of safety and therefore evacuation time. The key characteristics of a building that impact upon people s ability to evacuate in time of an emergency are ... 

Depth sensitivity is an equally important consideration in the analysis of surfaces. Techniques based on the detection of electrons or ions derive their surface sensitivity from the fact that these species cannot travel long distances in soflds without undergoing interactions which cause energy loss. If electrons are used as the basis of an analysis, the depth resolution will be relatively shallow and depend on both the energy of the incident and detected electrons and on characteristics of the material. In contrast, techniques based on high energy photons such as x-rays will sample a much greater depth due... 

The inelastic collision process is characterized by an inelastic mean free path, which is the distance traveled after which only 1/e of the Auger electrons maintain their initial energy. This is very important because only the electrons that escape the sample with their characteristic Auger energy are usefrd in identifying the atoms in... 

One could assume that this characteristic behavior of the mobility of the polymers is also reflected by the typical relaxation times r of the driven chains. Indeed, in Fig. 28 we show the relaxation time T2, determined from the condition g2( Z2) = - g/3 in dependence on the field B evidently, while for B < B t2 is nearly constant (or rises very slowly), for B > Be it grows dramatically. This result, as well as the characteristic variation of with B (cf. Figs. 27(a-c)), may be explained, at least phenomenologically, if the motion of a polymer chain through the host matrix is considered as consisting of (i) nearly free drift from one obstacle to another, and (ii) a period of trapping, r, of the molecule at the next obstacle. If the mean distance between obstacles is denoted by ( and the time needed by the chain to travel this distance is /, then - (/ t + /), whereby from Eq. (57) / = /Vq — k T/ DqBN). This gives a somewhat better approximation for the drift velocity... 

Injection Facility Overview describes the type of facility, its current status, and the characteristics of the injected wastes, and presents a brief history of injection and monitoring activities, including the distance traveled by the waste. 

The travel time f, is the time required for a contaminant cloud to reach the endpoint distance xe. As a first approximation, t, = xe/(ur/2) for ground-level clouds for elevated releases, t, = X/Ju where u is the characteristic wind speed. 

---