In this chapter, the flow-governing equations (conservation laws) are reviewed, with applications that are purposely turbomachinery related. Particular emphasis is placed on the total (or stagnation) flow properties. A turbomachinery-adapted Mach number definition is also introduced as a compressibility measure of the flow field. A considerable part of the chapter is devoted to the total-relative properties, which, together with the relative velocity, define a legitimate thermophysical state. Different means of gauging the performance of a turbomachine, and the wisdom behind each of them, are discussed. Also explored is the entropy-production principle, as a way of assessing the performance of turbomachinery components. The point is stressed that the calculation of entropy production may indeed be desirable, for it is the only meaningful performance measure that is accumulative (or addable) by its mere definition.

The case of Dr. P illustrates how brain damage can cause deficits in executive functions – which include the ability to plan actions to reach a goal, to use information flexibly, to think abstractly, and to make inferences. As illustrated by this case study, difficulties in executive function can arise despite normal functioning in other domains of intellectual processing, such as those measured by IQ tests (retention of knowledge, vocabulary, spatial processing abilities, and so forth).

The term executive function serves as an umbrella to describe a set of abilities. To better understand the types of abilities that we discuss in this chapter, let’s consider, by analogy, the skills and attributes required of a company executive. First, an executive must have a master plan. For example, the executive’s goal may be to increase customer satisfaction, diversify markets, or raise production.

The patient in the opening vignette of this chapter is known in the scientific literature by his initials, H.M. After realizing the unintended effects of the operation, his surgeon, Dr. Henry Scoville, contacted Brenda Milner and her colleagues at McGill University in Montreal to unravel the mystery of his memory loss. Professor Milner discovered the divide in H.M.’s memory that we just discussed: the paradox that while certain aspects of memory were lost after removal of his medial temporal lobe, others were retained (Scoville and Milner, 1957). This work was critical in demonstrating the existence of at least two separable systems that support our ability to remember. As noted by Eric Kandel, who won the Nobel Prize in Physiology and Medicine in 2000 for his work on the molecular mechanisms of memory formation, “[t]he study of H.M. by Brenda Milner stands as one of the great milestones in the history of modern neuroscience.

From a historical viewpoint, the centrifugal compressor configuration was developed and used, even in the propulsion field, well before axial-flow compressors were. Due to their large envelope and weight (Figure 11.1), the common belief that such a “bulky” compressor type has no place except in aerospace applications is not exactly accurate. For example, with a typical total-to-total pressure ratio of, for example, 5:1, it would take up to three axial-compressor stages to absorb similar amounts of shaft work that a single centrifugal compressor stage would. In fact, the added engine length, with so many axial stages, would increase the skin friction drag on the engine exterior, almost as much as the profile drag, which is a function of the frontal area.

The case study in the opening vignette illustrates some of the important ways that neuropsychological disorders observed developmentally can differ from those observed later in life. In adults, the inability to read is often associated with damage to particular regions of the left hemisphere (see Chapter 8). However, in Dan’s case, no evidence of localized brain damage was apparent. Whereas adults with alexia acquired the ability to read and then lost it, Dan never could read with a reasonable degree of proficiency. Thus, cognitive deficits can have different origins and different neural correlates, depending on whether they were acquired in adulthood or during the process of development.

The case of Dan and children with other developmental disabilities helps us to realize that the brain is dynamically changing.

As in other areas of cognitive neuroscience, much of what we know about the brain and mental illness has been based on observations of people with damage to the brain. The depression that led Joe Gray to suicide was most likely due to more than his inability to accept his impairments, although no doubt the loss of independence and reduced intellectual capacity contributed to his despair. Damage to parts of the left hemisphere, especially frontal regions and their interconnections, can often lead to clinical depression (Padmanabhan et al., 2019). Findings such as these underscore the importance of particular brain circuits in contributing to psychiatric disorders.

Fully understanding mental illness, or psychopathology, involves much more than understanding the brain. Psychopathology can be fruitfully approached from many different psychological perspectives, including not only the biological but also cognitive, social, and cross-cultural levels.

The brain seems to capture the public imagination like no other topic in science. Aided by striking color images intended to show “the brain in action,” media stories stoke the public’s interest in research that promises to reveal the secrets of human thought and behavior. Everyday people may look to neuroscience for a deeper understanding of their own behaviors or the behaviors of those around them. Scholars are actively exploring the potential relevance of cognitive neuroscience research to critical domains of society, including education, business, and the law, as seen in this chapter’s opening vignette. Meanwhile, profiteers may seek to capitalize on the public’s eagerness for “all things neuro” in order to make a dime. Yet, public enthusiasm notwithstanding, the science of the brain is very much in flux, as material from all the prior chapters can attest.

A central challenge, then, is to navigate the public dissemination of knowledge about neuroscience research such that legitimate findings with important societal implications can be separated from hype, even as knowledge in the field shifts from year to year.

The story about C.J. helps to illustrate that spatial processing is not a single cognitive function, but rather consists of many different abilities. Some of C.J.’s spatial abilities, such as understanding the relationship between the map and the surrounding terrain, and knowing geographical points of reference (north, south, east, and west), were compromised by her stroke, yet other abilities – such as determining left and right – were unaffected. In this chapter, we examine the many ways in which spatial relations among items can be computed and the brain systems that enable these computations.

We learned in Chapter 5 that the visual cortex provides a precise retinotopic map of space. However, a retinotopic map is inadequate for fully understanding the space around us. First, as we have already discussed in relation to object recognition, the retina only provides two-dimensional information about the three-dimensional world.

In this chapter we discuss the different methods used to understand how the brain influences the way we think, feel, and act. Because cognitive neuroscience is an interdisciplinary field of research, it requires integration of information about the brain with information about behavior. Depending on the question under investigation, we may want to obtain information about the brain at the neuroanatomical, neurochemical, or neurophysiological level.

At a neuroanatomical level, we may need information about the integrity of brain structures, their connections to other brain regions, and their relationship to particular behavioral patterns.

At other times, though, Brady was described as speaking in a “slow, measured cadence” (De Witt, 1990) that lacked the emotional inflections of normal speech.

After his injury, Brady also tended to be a bit more brutally honest than people in the political sphere are generally inclined to be. For example, he made highly unflattering remarks about some of his former colleagues in the White House, sometimes making those around him a bit uncomfortable (Bumiller, 1982). Although these tendencies may simply reflect the change in outlook that accompanies a brush with death, they may also reflect a failure of his damaged frontal lobes to inhibit socially inappropriate behavior.

A brief introduction to gas turbine engines was presented in Chapter 1. Review of the different engines included in this chapter reveals that most of these engine components are composed of “lifting” bodies, termed airfoil “cascades,” some of which are rotating, while others are stationary. These are all, by necessity, bound by the hub surface and the engine casing (or housing), as shown in Figures 2.1–2.5. As a result, the problem becomes one of the internal-aerodynamics type, as opposed to such traditional external-aerodynamics topics as “wing theory” and others. Referring, in particular, to the turbofan engines in Chapter 1 (e.g., Figure 1.3), these components may come in the form of ducted fans. These, as well as compressors and turbines, can be categorically summed up under the term “turbomachines.” Being unbound, however, the propeller of a turboprop engine (Figure 1.2) does not belong to the turbomachinery category.

The man you have just read about exhibits a phenomenon known as blindsight, which involves the retention of some visual capabilities without the conscious experience of seeing (Weiskrantz, 2009). What makes such cases so fascinating is that they raise a fundamental question: What does it really mean to “see”?

When you open your eyes, the visual world appears to you, seemingly without effort. The immediacy and apparent ease of visual awareness makes it hard to believe that a large proportion of your brain is working very hard to solve the complex problems of vision. In the brains of humans and other primates, visual processing is highly developed. The immense amount of brain tissue dedicated to sight enables us to have the exquisitely detailed color vision that is one of the hallmarks of being a primate.