Internal and External Pressures

Respondents note that there is a tense push and pull between external pressures from France, aid agencies, and macro trends in accreditation on the one hand and internal pressures from Tunisian politics, society, and culture on the other. This is 

Since statehood, respondents remark that the Tunisian model of education has always been based on the French system, which itself has recently been moving towards pan-European settings. However, respondents characterize the creation of the Bologna Process (Reinalda and Kulesza 2005) and the subsequent development of Euro-level standards (European Network for the Accreditation of Engineering Education Augusti et al. 2007) as a move more towards the American model. 

The internal Tunisian requirements often do not match with the impulse to send engineers abroad with an eye to reintegrate them (sometimes referred to as brain circulation Saxenian 2005). For students and workers who studied and worked abroad before returning to teach in Tunisia, numerous difficulties are described. Because of the necessary personal contacts to get recommendations, even initial steps are difficult and good research positions are hard to come by. Although the top students are seen as leaving for France, they are also seen as having many 

Students who come back from studying abroad have a different host of difficulties than graduates from Tunisian schools as they attempt to reintegrate themselves into the Tunisian workforce. International companies, however, are more willing to hire these individuals. Often, the students training has been more focused on practical experience— for example, if they studied in Germany—or at a more prestigious university in France. If the opportunity exists, students who studied in Tunisia are seen as likely to travel abroad for employment. 

Resporrdents observe a predictable hierarchy of choices for technical baccalaureates when they select their tertiary institutiorrs. There are no irrdicators available 

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The thickness of pipe bends shah be determined as for straight pipe, provided the bending operation does not result in a difference between maximum and minimum diameters greater than 8 and 3 percent of the nominal outside diameter of the pipe for internal and external pressure respectively. 

When we refer here to static pressure we mean the difference between internal and external pressure causing air to tend to flow into or out of ducts. Velocity pressure is that due to the air s forward movement. The sum of the two is total pressure. 

A pipe having a branch connection is weakened by the opening that must be made in it and, unless the wall thickness of the pipe is sufficiently in excess of that required to sustain the pressure, it is necessary to provide added reinforcement. The amount of reinforcement required to sustain the pressure shall be determined in accordance with para. IP-3.4.2 or IP-3.4.3. There are, however, certain branch connections which have adequate pressure strength or reinforcement as constructed. It may be assumed without calculation that a branch connection has adequate strength to sustain the internal and external pressure which will be applied to it if... 

Internal and External Pressure. The difference in pressure between the inside of a tank or its vapor space and local barometric or atmospheric pressure is called internal pressure. When the internal pressure is negative it is simply called a vacuum. The pressure is measured at the top of the liquid in the tank because the liquid itself exerts hydrostatic pressure, thus increasing to a maximum value at the base of the tank. 

The tank is specified to have a capacity of 1950 m3. This figure is the sum of one week production of nitric acid (1500 m3) plus an extra 450 m3. This extra 450 m3 capacity will be the normal tank operating level and is available for product sales to external markets. This represents approximately 20 standard road-tanker loads. The dimensions of the tank represent a standard specification available through the Denver Company (United States). The tank internal diameter is 15.2 m and the tank height required is 10.7 m. The internal and external pressure loads require a wall, base and roof plate thickness of 16 mm (a standard plate thickness available through BHP, Australia) to meet the Australian design code for pressure vessels (AS1 210). This thickness gives a 100% safety factor over the maximum anticipated stresses. 

To ensure the growth of the quality objective, management must resist both internal and external pressures which might subvert its... 

The adhesive formulator has many challenges in meeting the demands of the marketplace, and many of the tools that the formulator had utilized in the past are no longer acceptable. These internal and external pressures place the adhesive formulator in a special place among other professions. 

Special tests not specified by U.S. regulatory agencies were conducted to simulate expected service conditions. Dummy secondary capsules of the SR-Cf-100 series were subjected to internal and external pressures far in excess of pressures expected under the most adverse industrial service conditions. The special tests that successfully demonstrated the integrity of source construction and the seal welds were ... 

Spiralloy [Aqualon], TM for glass- and other filament-wound, resin-bonded internal and external pressure vessels. 

The greater force due to these collisions creates an initial increase in the force per unit area—or gas pressure—acting on the walls. This will cause the piston to rise, increasing the gas volume and decreasing the pressure until the internal and external pressure are once again equal (Figure 13.7). Take a minute or two to work out a similar series of steps to explain why decreased number of gas particles leads to decreased volume. 

Figure 3.10. Section of a bubble surface with internal and external pressures and and surface tension 7.

If the liquid is constrained in a capillary with very small radius, the difference between the internal and external pressures can become very large. Because of the large internal pressure, the liquid in the capillary will rise until it is balanced by the hydrostatic pressure of the rising liquid column. In this circumstance Eq. 3.61 becomes... 

Liquid systems with curved surfaces exhibit many unique properties (capillary rise, curvature-dependent vapor pressure, contact angle, difficulty of nuclea-tion) because of differences between internal and external pressures at the interface. 

Some items that must be considered are wind, earthquake, piping and support loads internal and external pressure and thermal loads. Stresses developed by these loads must be calculated separately and then combined with shell or head stresses caused by internal pressure at their point of application. These standards must be met whether or not a fatigue analysis is required. 

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