Engineering and Technology Journal

In the current paper, an experimental analysis on Al-sheet (AA 1050) with thickness 0.9 mm to reveal the effect of relevant forming factors on the formed thickness in two-point incremental forming (TPIF) process has been conducted. The formed thickness of pyramid-like shapes was analyzed by studying seven variables: die geometry, tool diameter, tool path, stepover, tool shape, lubricant and slope angle. The proposed analysis utilizes Box-Behnken design of experiment (BBD), main effects plot (MEP) and analysis of variance (ANOVA) for sake of studying the influences of the seven forming factors on the resulted thickness. The results of these analyses have indicated that the most significant factor affecting the formed thickness is the die geometry followed by tool shape, lubricant and stepover respectively for both slope angles of the pyramid. In addition, it has been found that the other variables have also significant effects on the formed thickness at both slopes of the pyramids produced.

Security is an important issue, especially in today’s technologically advanced society. Global System for Mobile Communications (GSM) is a world-wide standard for digital wireless communication. GSM uses A5/1 stream cipher in order to provide privacy on air communication. This paper introduce new improvements to the A5/1 stream cipher in order overcome the weakness that appear in clocking mechanism that used in A5/1 stream cipher. New S-box generation is proposed to increase the efficient for A5/1 majority function and improve randomness features. The randomness results confirm that the output bit-stream generated by the proposed stream cipher has improved the randomness performance.

The Box-Behnken Design (BBD) is used to model the sacrificial Cathodic
Protection System (SCPS) to find the factors effectiveness behaviour. For protection
potential assessment the BBD receives (resistivity of environment, sacrificial anode
alloy, distance between anode and cathode and surface area for the structure to be
protected) as input and gives the protection potential as output. By applying BBD
with their analysis tools we get many results. The important results which are the
factors individual effectiveness on the sacrificial cathodic protection (SCP) process
are the resistivity which has the greatest effect on the potential protection (rank=1)
followed by sacrificial anode alloy type (rank=2), surface area for structure protected
required (rank=3) and distance between anode and cathode (rank=4). The interaction
of sacrificial anode alloy and cathode area (χ2χ4) has significant effect on CP process
with the limits which are used in this work while the other factors interaction (χ1χ2,
χ1χ3, χ1χ4,χ2χ3, χ3χ4) has insignificant effect on the limits which used in this work.

1100 Al specimens were anodically oxidized in different concentrations of
tartaric acid-tartrate solution (pH=7) in 1, 1.75, 3.25 and 4 wt % at temperatures of
30, 37.5, 52.5 and 60 ºC by applying a range of potentials of 30, 37.5, 52.5 and 60
V at exposure times of 40, 47.5, 62.5 and 70 min.. These four variables are
manipulated through the experimental work using Box – Wilson experimental
design where second order polynomial model was proposed to correlate the studied
variables with the thickness of anodic film of aluminum alloy (1100) to estimate
the coefficients of the proposed polynomial adopted via statistica software.
Optimum conditions for achieving the maximum film thickness are obtained from
optimizing the above correlation and are found as follows: temp. = 44ºC, acid conc.
= 2.8 wt %, voltage = 43.6 V, time = 54.6 min.. Stagnate Solutions of 3, 5, 10 and
25 wt % Nacl at 25ºC have been investigated using polarization technique at
optimum conditions for anodizing. The most important feature achieved was the
great difference in behavior between the anodic polarization curves for bare and
anodized aluminum in different concentrations of Nacl solutions. The corrosion
rates for anodized specimens are lower than those for unanodized ones. The
polarization behavior of anodizing specimens shows that the breakdown potentials
are shifted to more noble direction than bare specimens which is more pronounced
in 25 wt % Nacl solution due to anodizing.

This paper will introduce two proposal algorithms (Snowfish 1) and the
(Snowfish 2) to improve the Sosemanuk stream cipher algorithm by benefiting from
the efficient properties of the Twofish block cipher and also use its key schedule, keydependent
Sbox to increase the security, randomness and try to avoid the guess and
determine attack of Sosemanuk. These two proposals use Twofish algorithm rather
than Serpent algorithm which was used in the Sosemanuk and also they use keydependent
Sbox rather than static Sbox. They are similar in the same key length (128
to 256 bit), IV length (128 bit), LFSR length, FSM functions and output
transformation.
In this paper will make a comparison between Snowfish 1, Snowfish 2 and
Sosemanuk algorithms by using the tests of randomness, the structural tests and the
complexity of the algorithm. These tests give results that show the two proposed
algorithms have good results in increasing the security and randomness compared
with Sosemanuk algorithm.

The main object of this work is to evaluate the possibility for using reasonable cement
content and fine materials to reduce costs of expensive chemical admixtures needed for the
manufacturing of self-compacting concrete (SCC). In this work, three values of cement content
are used (rich, medium and lean mixes) with cement content of 400, 300 and 250 kg/m3
respectively . Two maximum aggregate sizes of (10 and 20mm) for each cement content are
used. The powder content material is (cementations + filler ) is maintained constant (500kg/m3)
while the W/cm ratio ranges from 0.43 to 0.68. 10% Reactive Metakaolin Class N is used as a
partial replacement by weight of cement. On the other hand, limestone dust was used as a
partial replacement by weight of the powder content Tests were carried out on all mixes to
obtain the properties of fresh concrete in terms of viscosity and stability. The results showed that
increasing the percentage of filler (limestone dust) from 20% in rich mixes to50% in lean mixes
of the total weight of the powder content reduces the amount of cement in SCC without
significant effect on the fresh properties of the SCC mixes. This conclusion is significant from
the economical point of view. The mechanical properties of hardened SCC mixes are also
assessed. (compressive strength, modulus of elasticity ). The results obtained from this work
show that it is possible to produce SCC with different levels of cement content (250 to400kg/m3)
using local available materials which satisfy the requirements of this type of concrete .The test
data collected indicate that these materials can be used in the manufacturing of economical SCC.