The atomic bomb uses fission of heavy elements to produce a large amount of energy. It was designed and deployed during World War II by the United States military. The first test of an atomic bomb occurred in July 1945 in New Mexico and was given the name Trinity; this test was not declassified until 1949. In that year, Geoffrey Ingram Taylor released two papers detailing his process in calculating the energy yield of the atomic bomb from pictures of the Trinity explosion alone. Many scientists made similar calculations concurrently, although Taylor is often accredited with them. Since then, many scientists have also attempted to calculate a yield through various methods. This paper walks through these methods with a focus on Taylor’s method—based on first principles—as well as redoing the calculations that he performed with modern tools. In this paper, we make use of state-of-the-art computer vision tools to find a more precise measurement of the blast radius, as well as using curve fitting and numerical integration methods. With more precise measurements we are able to follow in Taylor’s footstep toward a more accurate approximation.

In this paper, we report the study of degradation for a kind of ideal mandrel material called poly-α-methylstyrene based on theoretical and experimental methods. First-principles calculations reveal two types of process: depolymerization and hydrogen-transfer-induced chain scission. The energy barrier for the former (0.68–0.82 eV) is smaller than that for most of the latter (1.39–4.23 eV). More importantly, reaction rates suggest that the former is fast whereas the latter is mostly slow, which can result in a difference of 5–31 orders of magnitude at 550 K. Furthermore, a thermogravimetric experiment shows that the activation energy of 2.53 eV for degradation is between those of fast and slow processes, corresponding to the theoretical average value of multiple reaction paths. Thus, a mandrel degradation model combining fast and slow processes is established at the atomic level. Our work provides a direction for research into the key technology of target fabrication in inertial confinement fusion.

This paper argues that Reid's first principle of design can be more widely accepted then one might suppose, due to the fact that it specifies no marks of design. Also it is explicated that the relation of the principle, on the one hand, and properly basic design beliefs on the other, is a relation of presupposition. It is furthermore suggested that Reid's discussion of what can be done in case of disagreement about first principles points to a position that is relevant to the current debates in the Epistemology of Disagreement literature and that merits further elaboration.

Reid had a theory of the human mind containing a theory of truth, both of our evidence of truth and the conditions of truth, fully consistent with empiricism. The justification and evidence of first principles is something felt in consciousness rather than some external relation. This is the result of our faculties, original and natural powers of our constitution. Original convictions and conceptions arise from our faculties in response to experience as a result of our natural development. Reid combines elements of foundationalism, coherentism, falliblism and nominalism. I distinguish and compare Reid to Hume, Moore, Quine, James and Wittgenstein.

What role do the first principles of morals play in Reid's moral theory? Reid has an official line regarding their role, which identifies these principles as foundational propositions that evidentially ground other moral propositions. I claim that, by Reid's own lights, this line of thought is mistaken. There is, however, another line of thought in Reid, one which identifies the first principles of morals as constitutive of moral thought. I explore this interpretation, arguing that it is a fruitful way of understanding much of what Reid wants to say about the role of moral first principles and drawing some connections between it and recent work on moral nonnaturalism.

By Reid's own account, ‘That the natural faculties, by which we distinguish truth from error, are not fallacious’ (FP#7), has a special place among the First Principles of Contingent Truths. Some have found that claim puzzling, but it is not. Contrary to what's usually assumed, certain FPs preceding FP#7 do not already assert the better part of what FP#7 explicitly states. FP#7 is needed because there is nothing epistemological in the FPs that precede it; and its special place among the FPs is a straightforward consequence of its being both perfectly general and distinctively epistemological.

This paper explains the nature and role of common sense in Reid and uses the exposition to answer some of Reid's critics. The key to defending Reid is to distinguish between two kinds of priority that common sense beliefs are supposed to enjoy. Common sense beliefs enjoy epistemological priority in that they constitute a foundation for knowledge; i.e. they have evidential status without being grounded in further evidence themselves. Common sense beliefs enjoy methodological priority in that they constrain philosophical theory: they serve as pre-theoretical commitments that philosophical theories ought to respect in the absence of good reasons for rejecting them.

This paper revisits Aquinas's understanding of theology as a science based on a participation in the divine scientia. Our modern presuppositions (in terms of “autonomous” reason and philosophy as a discipline utterly separate from theology) often appear to render Aquinas's claims implausible. In this contribution it is argued that (a) all sciences are fiduciary in the broad sense (with the exception of those that rely on principles per se nota) and (b) that first principles can only be accepted or rejected, but not refuted or demonstrated within the relevant discipline. From this, two conclusions can be drawn: first, despite its reliance on revelation theology's case is, therefore, not as peculiar as modern readers might initially assume: every discipline operates with key assumptions it simply accepts. Secondly, given the role of first principles, to characterise Aquinas's account of the assent of faith as fideist or voluntarist is beside the point, for you can only accept or reject first principles. The contribution ends by suggesting that assent to the articles of faith is not an extraneous acquiescence in assertions of divine authority either, as a reading of the first question of the Secunda Secundae makes clear. Indeed, the paper hints that we should not read the first question of the Prima Pars without engaging with the first questions of the Secunda Secundae.

First principles was carried out studying the properties of (Ti, Nb)C compounds based on density functional theory. The integration of mechanical behavior, electronic structures, and thermodynamic properties can be optimized by mediating the concentration of the titanium alloying element. The results revealed that these transition metal compounds were stable with the negative formation energy. Nb0.5Ti0.5C (29.15 GPa) demonstrated the largest hardness characterized by moduli (B, G) because of the stable shell configuration. NbC exhibited the strongest anisotropy from the universal anisotropic index (AU) and three-dimensional surface contours. TixNb1−xC compounds displayed relatively strong stress responses along the [001], [110], and [111] directions. Due to the weakening p–d bonding, the ideal tensile strength gradually decreased with the increasing titanium concentration. The electronic structures revealed that the bonding characteristics of the (Ti, Nb)C compounds were a mixture of metallic and covalent bonds. On the other hand, NbC and TiC exhibited a minimum (740.55 K) and maximum (919.29 K) Debye temperature, indicating the stronger metalic bonds of NbC and covalent bonds of TiC.

Hexagonal boron nitride (hBN) is a promising material for a range of applications including deep-ultraviolet light emission. Despite extensive experimental studies, some fundamental aspects of hBN remain unknown, such as the type of stacking faults likely to be present and their influence on electronic properties. In this paper, different stacking configurations of hBN are investigated using CASTEP, a pseudopotential density functional theory code. AB-b stacking faults, in which B atoms are positioned directly on top of one another while N atoms are located above the center of BN hexagons, are shown to be likely in conventional AB stacked hBN. Bandstructure calculations predict a single direct bandgap structure that may be responsible for the discrepancies in bandgap type observed experimentally. Calculations of the near edge structure showed that different stackings of hBN are distinguishable using measurements of core-loss edges in X-ray absorption and electron energy loss spectroscopy. AB stacking was found to best reproduce features in the experimental B and N K-edges. The calculations also show that splitting of the 1s to π* peak in the B K-edge, recently observed experimentally, may be accounted for by the presence of AB-b stacking faults.

With increased pressures coming from global competition and requirements for greater innovation in product development, designers are hard pressed to deliver designs of higher quality and variety using a repertoire of technological options from different disciplines. This interdisciplinary product development approach has not only removed many of the traditional constraints to design but has now given designers a much wider freedom of choice as to the best solution to a design problem. The focus of this paper is a knowledge-based design environment called Schemebuilder, which is a comprehensive and integrated suite of software tools aimed at supporting the designer in the rapid development of product design models in the conceptual, through embodiment stages of design. Illustrated is the use of the software tools in the qualitative generation of alternative schemes, by application of stored working and decomposition principles in the development of a function-means tree-like information structure. With mechatronic product development as the main theme, this paper describes a closely integrated methodology that incorporates a bond graph approach to continuous-time energetic systems and high-level Petri nets for the rigorous description of discrete-time information systems. Additionally, a technique is suggested for the decomposition of free format statements of need into the rigorously defined design context and required functions, which form the starting point of the function-means development process.

The pressure variation of the bandgap, at the isostructural phase transition of wurtzite InN, is determined theoretically, using the first-principles total-energy pseudopotential method. It is found that the bandgap (as well as the structural parameters) exhibit three different types of behavior, in three regions of pressure. Optical experiments at low temperatures could then be employed to directly identify the two different wurtzite phases of InN.