Stress Corrosion Cracking of Pressure Vessel Steel and Countermeasures by Titanium-Based & Cerium-Based Inhibitors in Subcritical Aqueous Environment

An overview of a severe kind of environmentally-assisted cracking-stress corrosion cracking (SCC) of pressure vessel steel (PVS),such as stainless steel 304, alloy 600,690 and other nickel-based alloys in subcritical (～300 ℃) aqueous environment was given. The mechanisms of SCC of metals under this inclement surrounding were briefly generalized. Herein,some pragmatic solutions to mitigate the SCC susceptibility and retard its propagation were presented. The titanium and cerium-based inhibitors addition countermeasure was highlighted.

Cold Flow Experiments and Acoustic Investigation on Pressure Oscillation Induced by Flow Instability

Pressure oscillation in solid rocket motor is believed to be the results of the interaction between the flow instability and the acoustics of combustion chamber.Several reasonable and necessary hypothesizes are given to establish an equation to describe this coupling.A cold flow motor called CVS60D(corner vortex shedding 60°)was designed to study the flow-acoustic coupling based on theoretical analysis.Experimental investigations were carried out to determine the acoustics of CVS60D.Corner vortex shedding is generated at the backward facing step which is designed similar to the geometry of the motor with finocyl propellant after the burnout of its fins.A pintle was used to modify the velocity in the duct to change the frequency of vortex shedding.It is found that large amplitude pressure oscillation occurs when the pintle moves to a range of specific position,which indicates that the frequency of vortex shedding is close to one order of acoustic modes of combustion chamber.The amplitude of pressure oscillation changes as the pintle moves.

CALCULATION OF GOLD SOLUBILITIES IN THE WINDOW OF T & P

Calculations based on the newest thermodynamic properties and supposed ore-fluid conditions suggest that gold solubilities in aqueous hydrosulphide and chloride fluids wi1l change with both temperature and pressure.At given 100 MPa, the gold solubility in aqueous hydrosulphide fluids will increase as the temperature increases, and reach the peak at 400℃, then decrease as the temperature increases;at 150 MPa, the peak of gold solubility is located at 500℃. At 100 MPa, however, the gold solubility in aqueous chloride fluids will also increase as the temperature increases, and reach the peak at 500℃, then decrease as the temperature increases ; at 150 MPa, the peak of gold solubility is shifted to 600℃ or higher. On the other hand, at given 300℃ and below 300℃,the gold solubility in aqueous hydrosulphide and chloride fluids changes very little as the pressure increases ; however, above 400℃ the gold solubility will increase sharply with pressure. This certifies that the pressure plays a very important role on the gold solubility at high temperature, At some content,the influence of pressure on the gold solubility is the same as that of temperature. Peaks of gold solubilities in aqueous hydrosulphide and chloride fluids in the window of T & P will form a trajectory respectively in the crust. The two trajectories will form a belt which is a favorite region for gold transportation in ore-forming fluids. Outside of this region, gold will be deposited from the ore-forming fluids. It is possible that the positions of gold deposits wou1d be inferred with this diagram in the future.

Influence of Seasonal Ground Water Level Fluctuations on the Stability of the Rohingya Refugee Camp Hills of Ukhiya, Teknaf, Cox’s Bazar, Bangladesh—A Threat for Sustainable Development

Bangladesh is a south Asian Monsoonal Country and the recent precipitation pattern in the Cox’s Bazar area of Bangladesh is changing and increasing the number of monsoonal slope failures and landslide hazards in the Kutubpalong & Balukhali Rohingya camp area. An attempt has been made to see the influence of seasonal variation of ground water level (G.W.L.) fluctuations on the stability of the eco hills and forests of Ukhiya Teknaf region. Ukhiya hills are in great danger because of cutting trees from the hill slopes and it is well established that due to recent change of climate, short term rainfall for few consecutive days during monsoon might show an influence on the factor of safety (Fs) values of the camp hill slopes. A clear G.W.L. variation between dry and wet seasons has an influence on the stability (Fs) values indicating that climate has a strong influence on the stability and threatening sustainable development. A stable or marginally stable slope might be unstable during raining and show a variation of ground water level (G.W.L.). The generation of pore water pressure (P.W.P.) is also influenced by seasonal variation of ground water level. During wet season negative P.W.P. called suction plays an important role to occur slope failures in the Ukhiya hills. Based on all calculated factor of safety values (Fs) at different locations, four (4) susceptible landslide risk zones are identified. They are very high risk (Fs = 0.18 to 0.46), high risk (Fs = 0.56 to 0.75), medium risk (Fs = 0.76 to 1.0) and marginally stable areas (Fs ≈ 1). Proper geo-engineering measures must be taken by the concerned authorizes to reduce P.W.P. during monsoon by installing rain water harvesting system, allowing sufficient drainage & other geotechnical measures to reduce the risk of slope failures in the Ukhiya hills. Based on the stability factor (Fs) at different slope locations of the camp hills, a risk map of the investigated area has been produced for the local community for their safety and to build up awareness & to motivate them to evacuate the site during monsoonal slope failures. The established “Risk Maps” can be used for future geological engineering works as well as for sustainable planning, design and construction purposes relating to adaptation and mitigation of landslide risks in the investigated area.

Evaluation of cilazapril in vasovagal syncope treatment

Objective: to evaluate cilazapril in vasovagal syncope treatment. Method: eighty\|six cases of VVS patients found positive in TTT tilt were medicated with 2.5 mg cilazapril daily for three months and followed up by TTT. Results: seven cases quit due to cough or unexplained reason; 79 VVS patients had no more fainting spells; 75.95% of TTT results of patients changed to negative after 3 months therapy. The before and after cilazapril treatment average blood pressures (taken in lying position) were 121/73 mm Hg (1 mm Hg= 0.133kPa) and 120/76 mm Hg respectively ( P > 0.05); and mean heart rates were 68.63±12.37/min and 70.13±13.15/min respectively with no significant changes ( P > 0.05). Conclusion: Cilazapril was effective in treatment of VVS; did not affect normal blood pressure and heart rate; was safe; and had little side effect.