Thermodynamic Modelling of Hydrogen-Multicomponent Alloy Systems: Calculating Pressure-Composition-Temperature Diagrams

<p>The applicability of an alloy as a hydrogen storage media mostly relies on its pressure-composition-temperature (PCT) diagram. Since the PCT diagram is composition-dependent, the vast compositional filed of high entropy alloys, complex concentrated alloys or multicomponent alloys can be explored to design alloys with optimized properties for each application. In this work, we present a thermodynamic model to calculate PCT diagrams of body-centered (BCC) multicomponent alloys. The entropy of the phases is described using the ideal configurational entropy for interstitial solid solutions with site blocking effect. As a first approximation, it is assumed that the H partial molar enthalpy of a phase is constant, so the enthalpy of H mixing varies linearly with the H concentration. Moreover, the H partial enthalpy of a phase for a multicomponent alloy was approximated by a simple ideal mixture law of this quantity for the alloy’s components with the same structure. Experimental data and DFT calculations were used for parametrization of the enthalpy terms of eight elements (Ti, V, Cr, Ni, Zr, Nb, Hf, and Ta), which are the components of the alloys tested in this work. Experimental PCTs of six BCC multicomponent alloys of four different systems were compared against the calculated ones and the agreement was remarkable. The model and parameters presented here can be regarded as a basis for developing powerful alloy design tools for different hydrogen storage applications.</p>

Thermodynamic Modelling of Hydrogen-Multicomponent Alloy Systems: Calculating Pressure-Composition-Temperature Diagrams

<p>The applicability of an alloy as a hydrogen storage media mostly relies on its pressure-composition-temperature (PCT) diagram. Since the PCT diagram is composition-dependent, the vast compositional filed of high entropy alloys, complex concentrated alloys or multicomponent alloys can be explored to design alloys with optimized properties for each application. In this work, we present a thermodynamic model to calculate PCT diagrams of body-centered (BCC) multicomponent alloys. The entropy of the phases is described using the ideal configurational entropy for interstitial solid solutions with site blocking effect. As a first approximation, it is assumed that the H partial molar enthalpy of a phase is constant, so the enthalpy of H mixing varies linearly with the H concentration. Moreover, the H partial enthalpy of a phase for a multicomponent alloy was approximated by a simple ideal mixture law of this quantity for the alloy’s components with the same structure. Experimental data and DFT calculations were used for parametrization of the enthalpy terms of eight elements (Ti, V, Cr, Ni, Zr, Nb, Hf, and Ta), which are the components of the alloys tested in this work. Experimental PCTs of six BCC multicomponent alloys of four different systems were compared against the calculated ones and the agreement was remarkable. The model and parameters presented here can be regarded as a basis for developing powerful alloy design tools for different hydrogen storage applications.</p>

Mengenal Ulama Sumatera Utara: Nukman Sulaiman dan Pemikiran Islamnya

This article depicts the life and works of Nukman Sulaiman descriptively. He is a Muslim learned man and a teacher who was born on 17 April 1917 in Perbaungan. Perbaungan is a district in Serdang Bedagai in North Sumatera, Indonesia. His parents are H. Abdul Aziz bin H. Sulaiman and Hj. Maimunah binti H. Mohd. Arif. At his at of 25, Nukman Sulaiman married a woman, Hajjah Siti Radiah binti Ahmad Anjang, on 14 Syawwal 1361 Higera or 25 Oktober 1942 AD. They live on STM Street or Sukajadi Street, Number 17, Medan.1 Nukman Sulaiman had eleven (11) children. Some of them live in Indonesia, and some other abroad.2 Durin his life, Nukman Sulaiman had a simple ideal; that is, to serve people as much as possible and to die with a good end (husnul khotimah). In fact, he realized this dream by developing al-Washliyah. Here, Nukman Sulaiman was directly involved in establishing Universitas Al-Washliyah (UNIVA/University of Al-Washliyah), and he had been serving himself as a rector of this university for about seventeen years (1970-1987). By this university, he aimed to generate Muslim learned men (`ulama’) as the heirs of the prophets’ teachings in Islam.

Determination of the applicability limits of the ideal gas model for the calculation of moist air properties

The submitted paper deals with the finding of such moist air states in which the components of moist air and hence the humid air itself can be described by the ideal gas model while maintaining a predefined accuracy. Both components of moist air (dry air and water vapor) can be described by a model of ideal gas at sufficiently low pressures and sufficiently high temperatures. In the paper, we are looking for such combinations of pressures and temperatures for both components, where the relative deviation in the density calculation using the ideal gas model does not exceed the desired value. In addition, on the basis of the mixture theory, such moist air conditions (characterized by pressure, temperature and specific humidity) are searched, on which the accuracy of the calculation meets the required conditions. Subsequently, diagrams are constructed that can be used to help identify the interface between a moist air area that can be described by a simple ideal gas model, and areas where it is necessary to use a more accurate model for one of the components.

The Romance of Democratic Transitions

This chapter more broadly analyzes the universe of democratic transitions. It explains why we tend to romanticize democratic transitions like most romantic comedies glamorize love: The people gather in a central square, start protesting, topple the dictatorship, hold elections, and live happily ever after. It further discusses why the on-the-ground facts often fail to live up to this simple ideal, why history is littered with failed attempts to democratize, and why even successful democratic transitions are often painfully long and violent. Ideally, of course, it would be enlightened civilians—not military leaders—who would depose an authoritarian government and promote, in concert with civil society, the conditions necessary for democratic development. But in many cases, civilian institutions are unable or unwilling to enable democracy, leaving the military to take charge.

La place du droit à la protection de la santé au regard du droit constitutionnel français

Cet article porte sur la notion d’État de droit dans le cadre d’un nouvel ordre international. La notion de droit consacre en quelque sorte sa prédominance générique au sein de l’Europe et tout particulièrement depuis la division physique et idéologique de ce continent. Le droit à la santé soulève quelques questions dans les pays où ce domaine est complètement envahi par les lois et un contexte économique ingrat. Le droit de la santé a été reconnu par la Constitution française en 1946 et désormais on voudrait qu’il soit reconnu comme une obligation par l’État et non seulement comme un simple idéal à réaliser. La Constitution de 1946, au sujet du droit de la santé a pris force constitutionnelle seulement depuis la décision rendue par le Conseil constitutionnel du 16 juillet 1971. D’abord, il faut voir quelle place aura le droit de la santé dans les paramètres constitutionnels en analysant les bases de la Constitution française en parallèle au droit à la protection de la santé, ainsi que le rôle et la place qu’a joués l’histoire dans la reconnaissance de ce droit. En effet, la Révolution de 1789 a affirmé les droits politiques mais a négligé considérablement les droits sociaux. Ce n’est qu’à l’arrivée de la Constitution du 4 novembre 1848 qu’il y eut un certain élargissement et que les droits sociaux ont eu une poussée fulgurante dans la sphère judiciaire. De plus, la question fondamentale sur le droit universel de la personne humaine sera fort importante dans la dénonciation du droit à la santé; plus précisément le caractère récent de la reconnaissance constitutionnelle du droit à la protection de la santé. Il est certes important de prendre en compte ce droit puisqu’il est reconnu et retenu dans le cadre du droit international des droits de l’homme. Alors que le droit à la santé peut être considéré comme un droit autonome et que dans les autres cas il n’est que le corollaire d’un autre droit constitutionnel, il faudra se pencher sur la nature juridique de la protection constitutionnelle de la santé pour en connaître ses tenants et aboutissants. Finalement, il faudra voir quelle sera la portée de la protection de la santé et la protection du corps humain, soit le principe de la dignité de la personne humaine. Nous constaterons que le Conseil constitutionnel a su mener progressivement le droit à la protection de la santé sur le chemin d’une reconnaissance effective notamment en reconnaissant le caractère essentiel du droit de la santé dans la société et ce, en passant par la notion de dignité humaine.