introduction: air temperature as an important climatic factor can influence variability and distribution of other climatic parameters. therefore, tracking the changes in air temperature is a popular procedure in climate change studies.. according to the national academy in the last decade, global temperature has raised 0.4 to 0.8⁰c. instrumental records show that, with the exception of 1998, th...

waterwashing or biodiesel purification is one of the steps in biodiesel fuel processing. waterwashing of the fuel is an indispensable processing stage, due to the presence of impurities in the fuel. in this research work, some of the effective parameters in biodiesel waterwashing and the optimum conditions which lead to economy in time and cost of waterwashing were investigated. the effective p...

the writers of this research have studied seven variables including: precipitation, relative humidity, sunny hours, temperature average, temperature minimum, temperature maximum and sea level pressure, at sanandaj air station during 1964-1994. sanandaj air station has nearly 10966 days of complete data for these variables. a principal component analysis (pca) has been applied on this data; then...

Analyzing the worst-case complexity of the k-level in a planar arrangement of n curves is a fundamental problem in combinatorial geometry. We give the first subquadratic upper bound (roughly O(nk1 2=3s)) for curves that are graphs of polynomial functions of an arbitrary fixed degree s. Previously, nontrivial results were known only for the case s = 1 and s = 2. We also improve the earlier bound...

The general communication tree embedding problem is the problem of mapping a set of communicating terminals, represented by a graph G, into the set of vertices of some physical network represented by a tree T . In the case where the vertices of G are mapped into the leaves of the host tree T the underlying tree is called a routing tree and if the internal vertices of T are forced to have degree...

Minimum Spanning Trees of weighted graphs are fundamental objects in numerous applications. In particular in distributed networks, the minimum spanning tree of the network is often used to route messages between network nodes. Unfortunately, while being most efficient in the total cost of connecting all nodes, minimum spanning trees fail miserably in the desired property of approximately preser...

This paper introduces the problem of fault tolerant topology control for one-to-all communications in symmetric wireless networks. We investigate two algorithms to address the problem, namely Minimum Weight Based Algorithm (MWBA) and Nearest Neighbor Augmentation Algorithm (NNAA), and prove that the former is a 4k approximation and the latter is a (k+4) approximation. Through simulations, we ev...