Intrusion work

The collection of ultrasonic data is relatively slow due to the need to collect the data from point locations. The results often give a relative condition only and as such a good knowledge of the structure is necessary. As with many non-destructive tests it is often necessary to calibrate the findings from limited targeted intrusive work. 

Intrusive work in soil contamination areas or fixed contamination areas. 

The construction industry has some unique characteristics. You may not think that you will encounter hazardous material when working on a construction project, but you must decide if there is a reasonable possibility that hazardous substances could be encountered during any intrusive... 

No matter if subcontractors are working for a general or main contractor or working directly for the client, when two or more prime contractors conduct activities at the same worksite, it is prudent that a common basis for health and safety rules and controls be established. Wlien one contractor performs an intrusive activity that increases the hazard level for all workers at a worksite, that information should be communicated to other contractors to permit them to plan and control their activities accordingly. 

The inherent reproducibility or imprecision of the method will have been determined as part of the validation procedure. This information can then be applied to the internal quality control programme which is designed to identify the intrusion of a bias (inaccuracy) and/or an alteration in the reproducibility of the assay. Programs for Internal quality control are most extensively developed for clinical laboratories because of the availability of suitable RMs in large batches and at an affordable cost although some level of IQC is appropriate to aU work carried out at a continuing basis see Section 6.2. 

The earliest estimates of the enol content of various p-diketones was made by careful distillation (Meyer and Schoeller, 1920 Meyer and Hopflf, 1921). Although, as a method of studying the equilibrium, this approach has been replaced by non-intrusive methods, work on the physical separation of the tautomers has continued (e.g. Regitzand Schafer, 1981 Vogt and Gompper, 1981). 

Work concentrated on gangue quartz in main gold-bearing sulfides veins, and in late stage intrusion-related ( ) base-metal veins. Polished sections were first investigated by transmitted and reflected light microscopy to find suitable samples... 

Wallace Carothers and coworkers at DuPont synthesized aliphatic polyesters in the 1930s [Furukawa, 1998 Hounshell and Smith, 1988]. These had melting points below 100°C, which made them unsuitable for firber use. Carothers then turned successfully to polyamides, based on the theoretical consideration that amides melt higher than esters. Polyamides were the first synthetic fibers to be produced commercially. The polyester and polyamide research at DuPont had a major impact on all of polymer science. Carothers laid the foundation for much of our understanding of how to synthesize polymeric materials. Out of that work came other discoveries in the late 1930s, including neoprene, an elastomer produced from chloro-prene, and Teflon, produced from tetrafluoroethylene. The initial commercial application for nylon 6/6 was women s hosiery, but this was short-lived with the intrusion of World War II. The entire nylon 6/6 production was allocated to the war effort in applications for parachutes, tire cord, sewing thread, and rope. The civilian applications for nylon products burst forth and expanded rapidly after the war. 

As an employer who has to manage safety critical applications, do not use drug tests to test for impairment. It does not work. This strategy leads to the elimination of drug-free workers (in cases of false positives), and it also fails to catch workers who are impaired (false negatives). False negatives can lead to disasters. Use impairment tests such as that developed by Performance Factors Impairment tests are not intrusive, they are more cost effective and take less time to administer, and they test impairment rather than lifestyle. 

The pressure-volume (P-fO work associated with an initial intrusion-extrusion cycle can be calculated from the areas above curves A and C to the maximum intruded volume, indicated by the horizontal dotted line in Fig. 12.1. (The work associated with any graphical area can be calculated with reference to equations (11.8) and (11.9).) This P-V work, I dlTj, can be expressed as... 

Even in the absence of mercury entrapment, second or subsequent intrusion-extrusion cycles, curves B and C of Fig. 12.1, continue to show hysteresis with the P-V work, dW2, through a cycle given by... 

Equations (12.1) and (12.2) indicate that the work of intrusion always... 

The total area above the first intrusion curve, A in Fig. 12.1, to the maximum intruded volume indicated by the horizontal dotted line, corresponds to the P-V work of intrusion, IFj. This work term consists of three parts, the first of which is the work of entrapment, W, corresponding to the area between curves A and B. The second contribution to IF. is the work, fV g, associated with the contact angle change from 0, to 0 ... 

The work of extrusion using the incorrect or intrusion contact angle is given by... 

It would appear from equations (12.7) and (12.8) that there are two different values for W, the work of extrusion. This is not the case. When equation (12.7) is used to calculate the work of extrusion, A is determined from Fig. 12.1 where the intrusion contact angle 6- was used to obtain the extrusion curve. In fact, A is a smaller area than that of the pores actually emptied. When equation (12.8) is employed A represents the correct pore area and is larger than A by the factor cos 0 /cos 0. Thus, regardless of whether equation (12.7) or (12.8) is used, the calculated value of will be the same. 

The values of the work terms for numerous samples, calculated from equations (12.10), (12.11) and (12.12), show excellent agreement with the corresponding work terms obtained by graphical integration of the areas in the intrusion-extrusion cycles. 

Intrusion with contact angle 6 into pores with area A, for which the corresponding work, Ifi, is... 

Summing all of the above work terms (1-5), with positive work being done on the system and the negative sign indicating work done by the system, leads to the total work dWi around a first intrusion-extrusion cycle. That is,... 

The P-V work differences between intrusion and extrusion, corresponding to the area between curves. A and C of Fig. 12.1 can be expressed as... 

When the additional work terms fV, W g and Ware considered the difference in the work of intrusion and extrusion is written as... 

Since IF = 0 and since no work difference exists between and for any element of the intrusion-extrusion curve, it follows that hysteresis on volume-pressure plots results only as a consequence of ignoring the additional energy terms and... 

---