Since we do not know in advance the exact distribution of the channel conditions, and the number of users may also change, it is difficult to obtain vector in advance.
The magnetic characteristic is defined from the vector relation between the magnetic field strength vector H and the magnetic flux density vector B. It is very difficult to express the vector relation by using the conventional constitutive equation B = μH.
"Generals can't control agents that rely on air currents to disperse them, and it was difficult to use the vector precisely, so it fell out of favor.
It is not difficult to prove that vector U = ( U C U R ) T is a solution of minimization problem (4) and (5) if and only if U C is a solution of the problem (8) and U R is determined by equation (9).
Consistency of the findings in households reporting no case of dengue in the previous year makes it difficult to explain by vector control programs placing the temephos in response to reported cases.
Problem (2) is proved to be an NP-hard problem, so it is very difficult to solve the beamforming vector directly.
Moderate transitions and broad mosaics are difficult to indicate in a vector vegetation map, whereas RS probabilistic classifications can output images indicating core areas, important for key species and biodiversity pattern, and transitional zones, important for ecosystem processes and perhaps plant evolution, which distinction is important for conservation planning.
However, the opposite direction is difficult to accomplish: A given vector field in general can not easily be converted to a graph.
In earlier studies, the clinostat was rotated only in a single dimension (1D), such as horizontal rotation [21] or vertical rotation [22], [23], which generated extra centrifugal forces and made it difficult to nullify the gravitation vector fully.
However, in contrast to many other tissues, keratinocytes are relatively difficult to transduce by adenoviral vectors.
